
/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


#if (NGX_HTTP_CACHE)
static ngx_int_t ngx_http_upstream_cache(ngx_http_request_t *r,
                                         ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_cache_send(ngx_http_request_t *r,
                                              ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_cache_status(ngx_http_request_t *r,
                                                ngx_http_variable_value_t *v, uintptr_t data);
#endif

static void ngx_http_upstream_init_request(ngx_http_request_t *r);
static void ngx_http_upstream_resolve_handler(ngx_resolver_ctx_t *ctx);
static void ngx_http_upstream_rd_check_broken_connection(ngx_http_request_t *r);
static void ngx_http_upstream_wr_check_broken_connection(ngx_http_request_t *r);
static void ngx_http_upstream_check_broken_connection(ngx_http_request_t *r,
                                                      ngx_event_t *ev);
static void ngx_http_upstream_connect(ngx_http_request_t *r,
                                      ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_reinit(ngx_http_request_t *r,
                                          ngx_http_upstream_t *u);
static void ngx_http_upstream_send_request(ngx_http_request_t *r,
                                           ngx_http_upstream_t *u);
static void ngx_http_upstream_send_request_handler(ngx_http_request_t *r,
                                                   ngx_http_upstream_t *u);
static void ngx_http_upstream_process_header(ngx_http_request_t *r,
                                             ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_test_next(ngx_http_request_t *r,
                                             ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_intercept_errors(ngx_http_request_t *r,
                                                    ngx_http_upstream_t *u);
static ngx_int_t ngx_http_upstream_test_connect(ngx_connection_t *c);
static ngx_int_t ngx_http_upstream_process_headers(ngx_http_request_t *r,
                                                   ngx_http_upstream_t *u);
static void ngx_http_upstream_process_body_in_memory(ngx_http_request_t *r,
                                                     ngx_http_upstream_t *u);
static void ngx_http_upstream_send_response(ngx_http_request_t *r,
                                            ngx_http_upstream_t *u);
static void
ngx_http_upstream_process_non_buffered_downstream(ngx_http_request_t *r);
static void
ngx_http_upstream_process_non_buffered_upstream(ngx_http_request_t *r,
                                                ngx_http_upstream_t *u);
static void
ngx_http_upstream_process_non_buffered_request(ngx_http_request_t *r,
                                               ngx_uint_t do_write);
static ngx_int_t ngx_http_upstream_non_buffered_filter_init(void *data);
static ngx_int_t ngx_http_upstream_non_buffered_filter(void *data,
                                                       ssize_t bytes);
static void ngx_http_upstream_process_downstream(ngx_http_request_t *r);
static void ngx_http_upstream_process_upstream(ngx_http_request_t *r,
                                               ngx_http_upstream_t *u);
static void ngx_http_upstream_process_request(ngx_http_request_t *r);
static void ngx_http_upstream_store(ngx_http_request_t *r,
                                    ngx_http_upstream_t *u);
static void ngx_http_upstream_dummy_handler(ngx_http_request_t *r,
                                            ngx_http_upstream_t *u);
static void ngx_http_upstream_next(ngx_http_request_t *r,
                                   ngx_http_upstream_t *u, ngx_uint_t ft_type);
static void ngx_http_upstream_cleanup(void *data);
static void ngx_http_upstream_finalize_request(ngx_http_request_t *r,
                                               ngx_http_upstream_t *u, ngx_int_t rc);

static ngx_int_t ngx_http_upstream_process_header_line(ngx_http_request_t *r,
                                                       ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_content_length(ngx_http_request_t *r,
                                                          ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_set_cookie(ngx_http_request_t *r,
                                                      ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t
ngx_http_upstream_process_cache_control(ngx_http_request_t *r,
                                        ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_ignore_header_line(ngx_http_request_t *r,
                                                      ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_expires(ngx_http_request_t *r,
                                                   ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_accel_expires(ngx_http_request_t *r,
                                                         ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_limit_rate(ngx_http_request_t *r,
                                                      ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_buffering(ngx_http_request_t *r,
                                                     ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_charset(ngx_http_request_t *r,
                                                   ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_process_connection(ngx_http_request_t *r,
                                                      ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t
ngx_http_upstream_process_transfer_encoding(ngx_http_request_t *r,
                                            ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_header_line(ngx_http_request_t *r,
                                                    ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t
ngx_http_upstream_copy_multi_header_lines(ngx_http_request_t *r,
                                          ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_content_type(ngx_http_request_t *r,
                                                     ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_last_modified(ngx_http_request_t *r,
                                                      ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_rewrite_location(ngx_http_request_t *r,
                                                    ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_rewrite_refresh(ngx_http_request_t *r,
                                                   ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_rewrite_set_cookie(ngx_http_request_t *r,
                                                      ngx_table_elt_t *h, ngx_uint_t offset);
static ngx_int_t ngx_http_upstream_copy_allow_ranges(ngx_http_request_t *r,
                                                     ngx_table_elt_t *h, ngx_uint_t offset);

#if (NGX_HTTP_GZIP)
static ngx_int_t ngx_http_upstream_copy_content_encoding(ngx_http_request_t *r,
                                                         ngx_table_elt_t *h, ngx_uint_t offset);
#endif

static ngx_int_t ngx_http_upstream_add_variables(ngx_conf_t *cf);
static ngx_int_t ngx_http_upstream_addr_variable(ngx_http_request_t *r,
                                                 ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_status_variable(ngx_http_request_t *r,
                                                   ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_response_time_variable(ngx_http_request_t *r,
                                                          ngx_http_variable_value_t *v, uintptr_t data);
static ngx_int_t ngx_http_upstream_response_length_variable(
    ngx_http_request_t *r, ngx_http_variable_value_t *v, uintptr_t data);

static char *ngx_http_upstream(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy);
static char *ngx_http_upstream_server(ngx_conf_t *cf, ngx_command_t *cmd,
                                      void *conf);

static void *ngx_http_upstream_create_main_conf(ngx_conf_t *cf);
static char *ngx_http_upstream_init_main_conf(ngx_conf_t *cf, void *conf);

#if (NGX_HTTP_SSL)
static void ngx_http_upstream_ssl_init_connection(ngx_http_request_t *,
                                                  ngx_http_upstream_t *u, ngx_connection_t *c);
static void ngx_http_upstream_ssl_handshake(ngx_connection_t *c);
#endif


ngx_http_upstream_header_t  ngx_http_upstream_headers_in[] = {

  { ngx_string("Status"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, status),
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("Content-Type"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, content_type),
    ngx_http_upstream_copy_content_type, 0, 1 },

  { ngx_string("Content-Length"),
    ngx_http_upstream_process_content_length,
    offsetof(ngx_http_upstream_headers_in_t, content_length),
    ngx_http_upstream_ignore_header_line, 0, 0 },

  { ngx_string("Date"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, date),
    ngx_http_upstream_copy_header_line,
    offsetof(ngx_http_headers_out_t, date), 0 },

  { ngx_string("Last-Modified"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, last_modified),
    ngx_http_upstream_copy_last_modified, 0, 0 },

  { ngx_string("ETag"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, etag),
    ngx_http_upstream_copy_header_line,
    offsetof(ngx_http_headers_out_t, etag), 0 },

  { ngx_string("Server"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, server),
    ngx_http_upstream_copy_header_line,
    offsetof(ngx_http_headers_out_t, server), 0 },

  { ngx_string("WWW-Authenticate"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, www_authenticate),
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("Location"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, location),
    ngx_http_upstream_rewrite_location, 0, 0 },

  { ngx_string("Refresh"),
    ngx_http_upstream_ignore_header_line, 0,
    ngx_http_upstream_rewrite_refresh, 0, 0 },

  { ngx_string("Set-Cookie"),
    ngx_http_upstream_process_set_cookie, 0,
    ngx_http_upstream_rewrite_set_cookie, 0, 1 },

  { ngx_string("Content-Disposition"),
    ngx_http_upstream_ignore_header_line, 0,
    ngx_http_upstream_copy_header_line, 0, 1 },

  { ngx_string("Cache-Control"),
    ngx_http_upstream_process_cache_control, 0,
    ngx_http_upstream_copy_multi_header_lines,
    offsetof(ngx_http_headers_out_t, cache_control), 1 },

  { ngx_string("Expires"),
    ngx_http_upstream_process_expires, 0,
    ngx_http_upstream_copy_header_line,
    offsetof(ngx_http_headers_out_t, expires), 1 },

  { ngx_string("Accept-Ranges"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, accept_ranges),
    ngx_http_upstream_copy_allow_ranges,
    offsetof(ngx_http_headers_out_t, accept_ranges), 1 },

  { ngx_string("Connection"),
    ngx_http_upstream_process_connection, 0,
    ngx_http_upstream_ignore_header_line, 0, 0 },

  { ngx_string("Keep-Alive"),
    ngx_http_upstream_ignore_header_line, 0,
    ngx_http_upstream_ignore_header_line, 0, 0 },

  { ngx_string("X-Powered-By"),
    ngx_http_upstream_ignore_header_line, 0,
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("X-Accel-Expires"),
    ngx_http_upstream_process_accel_expires, 0,
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("X-Accel-Redirect"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, x_accel_redirect),
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("X-Accel-Limit-Rate"),
    ngx_http_upstream_process_limit_rate, 0,
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("X-Accel-Buffering"),
    ngx_http_upstream_process_buffering, 0,
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("X-Accel-Charset"),
    ngx_http_upstream_process_charset, 0,
    ngx_http_upstream_copy_header_line, 0, 0 },

  { ngx_string("Transfer-Encoding"),
    ngx_http_upstream_process_transfer_encoding, 0,
    ngx_http_upstream_ignore_header_line, 0, 0 },

#if (NGX_HTTP_GZIP)
  { ngx_string("Content-Encoding"),
    ngx_http_upstream_process_header_line,
    offsetof(ngx_http_upstream_headers_in_t, content_encoding),
    ngx_http_upstream_copy_content_encoding, 0, 0 },
#endif

  { ngx_null_string, NULL, 0, NULL, 0, 0 }
};


static ngx_command_t  ngx_http_upstream_commands[] = {

  { ngx_string("upstream"),
    NGX_HTTP_MAIN_CONF|NGX_CONF_BLOCK|NGX_CONF_TAKE1,
    ngx_http_upstream,
    0,
    0,
    NULL },

  { ngx_string("server"),
    NGX_HTTP_UPS_CONF|NGX_CONF_1MORE,
    ngx_http_upstream_server,
    NGX_HTTP_SRV_CONF_OFFSET,
    0,
    NULL },

  ngx_null_command
};


static ngx_http_module_t  ngx_http_upstream_module_ctx = {
  ngx_http_upstream_add_variables,       /* preconfiguration */
  NULL,                                  /* postconfiguration */

  ngx_http_upstream_create_main_conf,    /* create main configuration */
  ngx_http_upstream_init_main_conf,      /* init main configuration */

  NULL,                                  /* create server configuration */
  NULL,                                  /* merge server configuration */

  NULL,                                  /* create location configuration */
  NULL                                   /* merge location configuration */
};


ngx_module_t  ngx_http_upstream_module = {
  NGX_MODULE_V1,
  &ngx_http_upstream_module_ctx,         /* module context */
  ngx_http_upstream_commands,            /* module directives */
  NGX_HTTP_MODULE,                       /* module type */
  NULL,                                  /* init master */
  NULL,                                  /* init module */
  NULL,                                  /* init process */
  NULL,                                  /* init thread */
  NULL,                                  /* exit thread */
  NULL,                                  /* exit process */
  NULL,                                  /* exit master */
  NGX_MODULE_V1_PADDING
};


static ngx_http_variable_t  ngx_http_upstream_vars[] = {

  { ngx_string("upstream_addr"), NULL,
    ngx_http_upstream_addr_variable, 0,
    NGX_HTTP_VAR_NOCACHEABLE, 0 },

  { ngx_string("upstream_status"), NULL,
    ngx_http_upstream_status_variable, 0,
    NGX_HTTP_VAR_NOCACHEABLE, 0 },

  { ngx_string("upstream_response_time"), NULL,
    ngx_http_upstream_response_time_variable, 0,
    NGX_HTTP_VAR_NOCACHEABLE, 0 },

  { ngx_string("upstream_response_length"), NULL,
    ngx_http_upstream_response_length_variable, 0,
    NGX_HTTP_VAR_NOCACHEABLE, 0 },

#if (NGX_HTTP_CACHE)

  { ngx_string("upstream_cache_status"), NULL,
    ngx_http_upstream_cache_status, 0,
    NGX_HTTP_VAR_NOCACHEABLE, 0 },

#endif

  { ngx_null_string, NULL, NULL, 0, 0, 0 }
};


static ngx_http_upstream_next_t  ngx_http_upstream_next_errors[] = {
  { 500, NGX_HTTP_UPSTREAM_FT_HTTP_500 },
  { 502, NGX_HTTP_UPSTREAM_FT_HTTP_502 },
  { 503, NGX_HTTP_UPSTREAM_FT_HTTP_503 },
  { 504, NGX_HTTP_UPSTREAM_FT_HTTP_504 },
  { 404, NGX_HTTP_UPSTREAM_FT_HTTP_404 },
  { 0, 0 }
};


ngx_conf_bitmask_t  ngx_http_upstream_cache_method_mask[] = {
  { ngx_string("GET"),  NGX_HTTP_GET},
  { ngx_string("HEAD"), NGX_HTTP_HEAD },
  { ngx_string("POST"), NGX_HTTP_POST },
  { ngx_null_string, 0 }
};


ngx_conf_bitmask_t  ngx_http_upstream_ignore_headers_masks[] = {
  { ngx_string("X-Accel-Redirect"), NGX_HTTP_UPSTREAM_IGN_XA_REDIRECT },
  { ngx_string("X-Accel-Expires"), NGX_HTTP_UPSTREAM_IGN_XA_EXPIRES },
  { ngx_string("X-Accel-Limit-Rate"), NGX_HTTP_UPSTREAM_IGN_XA_LIMIT_RATE },
  { ngx_string("X-Accel-Buffering"), NGX_HTTP_UPSTREAM_IGN_XA_BUFFERING },
  { ngx_string("X-Accel-Charset"), NGX_HTTP_UPSTREAM_IGN_XA_CHARSET },
  { ngx_string("Expires"), NGX_HTTP_UPSTREAM_IGN_EXPIRES },
  { ngx_string("Cache-Control"), NGX_HTTP_UPSTREAM_IGN_CACHE_CONTROL },
  { ngx_string("Set-Cookie"), NGX_HTTP_UPSTREAM_IGN_SET_COOKIE },
  { ngx_null_string, 0 }
};


ngx_int_t
ngx_http_upstream_create(ngx_http_request_t *r)
{
  ngx_http_upstream_t  *u;

  u = r->upstream;

  if (u && u->cleanup) {
    r->main->count++;
    ngx_http_upstream_cleanup(r);
  }

  u = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_t));
  if (u == NULL) {
    return NGX_ERROR;
  }

  r->upstream = u;

  u->peer.log = r->connection->log;
  u->peer.log_error = NGX_ERROR_ERR;
#if (NGX_THREADS)
  u->peer.lock = &r->connection->lock;
#endif

#if (NGX_HTTP_CACHE)
  r->cache = NULL;
#endif

  u->headers_in.content_length_n = -1;

  return NGX_OK;
}


void
ngx_http_upstream_init(ngx_http_request_t *r)
{
  ngx_connection_t     *c;

  c = r->connection;

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http init upstream, client timer: %d", c->read->timer_set);

  if (c->read->timer_set) {
    ngx_del_timer(c->read);
  }

  if (ngx_event_flags & NGX_USE_CLEAR_EVENT) {

    if (!c->write->active) {
      if (ngx_add_event(c->write, NGX_WRITE_EVENT, NGX_CLEAR_EVENT)
          == NGX_ERROR)
      {
        ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
      }
    }
  }

  ngx_http_upstream_init_request(r);
}


static void
ngx_http_upstream_init_request(ngx_http_request_t *r)
{
  ngx_str_t                      *host;
  ngx_uint_t                      i;
  ngx_resolver_ctx_t             *ctx, temp;
  ngx_http_cleanup_t             *cln;
  ngx_http_upstream_t            *u;
  ngx_http_core_loc_conf_t       *clcf;
  ngx_http_upstream_srv_conf_t   *uscf, **uscfp;
  ngx_http_upstream_main_conf_t  *umcf;

  if (r->aio) {
    return;
  }

  u = r->upstream;

#if (NGX_HTTP_CACHE)

  if (u->conf->cache) {
    ngx_int_t  rc;

    rc = ngx_http_upstream_cache(r, u);

    if (rc == NGX_BUSY) {
      r->write_event_handler = ngx_http_upstream_init_request;
      return;
    }

    r->write_event_handler = ngx_http_request_empty_handler;

    if (rc == NGX_DONE) {
      return;
    }

    if (rc != NGX_DECLINED) {
      ngx_http_finalize_request(r, rc);
      return;
    }
  }

#endif

  u->store = (u->conf->store || u->conf->store_lengths);

  if (!u->store && !r->post_action && !u->conf->ignore_client_abort) {
    r->read_event_handler = ngx_http_upstream_rd_check_broken_connection;
    r->write_event_handler = ngx_http_upstream_wr_check_broken_connection;
  }

  if (r->request_body) {
    u->request_bufs = r->request_body->bufs;
  }

  if (u->create_request(r) != NGX_OK) {
    ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  u->peer.local = u->conf->local;

  clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

  u->output.alignment = clcf->directio_alignment;
  u->output.pool = r->pool;
  u->output.bufs.num = 1;
  u->output.bufs.size = clcf->client_body_buffer_size;
  u->output.output_filter = ngx_chain_writer;
  u->output.filter_ctx = &u->writer;

  u->writer.pool = r->pool;

  if (r->upstream_states == NULL) {

    r->upstream_states = ngx_array_create(r->pool, 1,
                                          sizeof(ngx_http_upstream_state_t));
    if (r->upstream_states == NULL) {
      ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

  } else {

    u->state = ngx_array_push(r->upstream_states);
    if (u->state == NULL) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));
  }

  cln = ngx_http_cleanup_add(r, 0);
  if (cln == NULL) {
    ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  cln->handler = ngx_http_upstream_cleanup;
  cln->data = r;
  u->cleanup = &cln->handler;

  if (u->resolved == NULL) {

    uscf = u->conf->upstream;

  } else {

    if (u->resolved->sockaddr) {

      if (ngx_http_upstream_create_round_robin_peer(r, u->resolved)
          != NGX_OK)
      {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
      }

      ngx_http_upstream_connect(r, u);

      return;
    }

    host = &u->resolved->host;

    umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);

    uscfp = umcf->upstreams.elts;

    for (i = 0; i < umcf->upstreams.nelts; i++) {

      uscf = uscfp[i];

      if (uscf->host.len == host->len
          && ((uscf->port == 0 && u->resolved->no_port)
              || uscf->port == u->resolved->port)
          && ngx_memcmp(uscf->host.data, host->data, host->len) == 0)
      {
        goto found;
      }
    }

    if (u->resolved->port == 0) {
      ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                    "no port in upstream \"%V\"", host);
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    temp.name = *host;

    ctx = ngx_resolve_start(clcf->resolver, &temp);
    if (ctx == NULL) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    if (ctx == NGX_NO_RESOLVER) {
      ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                    "no resolver defined to resolve %V", host);

      ngx_http_upstream_finalize_request(r, u, NGX_HTTP_BAD_GATEWAY);
      return;
    }

    ctx->name = *host;
    ctx->type = NGX_RESOLVE_A;
    ctx->handler = ngx_http_upstream_resolve_handler;
    ctx->data = r;
    ctx->timeout = clcf->resolver_timeout;

    u->resolved->ctx = ctx;

    if (ngx_resolve_name(ctx) != NGX_OK) {
      u->resolved->ctx = NULL;
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    return;
  }

found:

  if (uscf->peer.init(r, uscf) != NGX_OK) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  ngx_http_upstream_connect(r, u);
}


#if (NGX_HTTP_CACHE)

static ngx_int_t
ngx_http_upstream_cache(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_int_t          rc;
  ngx_http_cache_t  *c;

  c = r->cache;

  if (c == NULL) {

    if (!(r->method & u->conf->cache_methods)) {
      return NGX_DECLINED;
    }

    if (r->method & NGX_HTTP_HEAD) {
      u->method = ngx_http_core_get_method;
    }

    if (ngx_http_file_cache_new(r) != NGX_OK) {
      return NGX_ERROR;
    }

    if (u->create_key(r) != NGX_OK) {
      return NGX_ERROR;
    }

    /* TODO: add keys */

    ngx_http_file_cache_create_key(r);

    if (r->cache->header_start + 256 >= u->conf->buffer_size) {
      ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                    "%V_buffer_size %uz is not enough for cache key, "
                    "it should increased at least to %uz",
                    &u->conf->module, u->conf->buffer_size,
                    ngx_align(r->cache->header_start + 256, 1024));

      r->cache = NULL;
      return NGX_DECLINED;
    }

    u->cacheable = 1;

    switch (ngx_http_test_predicates(r, u->conf->cache_bypass)) {

      case NGX_ERROR:
        return NGX_ERROR;

      case NGX_DECLINED:
        u->cache_status = NGX_HTTP_CACHE_BYPASS;
        return NGX_DECLINED;

      default: /* NGX_OK */
        break;
    }

    c = r->cache;

    c->min_uses = u->conf->cache_min_uses;
    c->body_start = u->conf->buffer_size;
    c->file_cache = u->conf->cache->data;

    c->lock = u->conf->cache_lock;
    c->lock_timeout = u->conf->cache_lock_timeout;

    u->cache_status = NGX_HTTP_CACHE_MISS;
  }

  rc = ngx_http_file_cache_open(r);

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "http upstream cache: %i", rc);

  switch (rc) {

    case NGX_HTTP_CACHE_UPDATING:

      if (u->conf->cache_use_stale & NGX_HTTP_UPSTREAM_FT_UPDATING) {
        u->cache_status = rc;
        rc = NGX_OK;

      } else {
        rc = NGX_HTTP_CACHE_STALE;
      }

      break;

    case NGX_OK:
      u->cache_status = NGX_HTTP_CACHE_HIT;
  }

  switch (rc) {

    case NGX_OK:

      rc = ngx_http_upstream_cache_send(r, u);

      if (rc != NGX_HTTP_UPSTREAM_INVALID_HEADER) {
        return rc;
      }

      break;

    case NGX_HTTP_CACHE_STALE:

      c->valid_sec = 0;
      u->buffer.start = NULL;
      u->cache_status = NGX_HTTP_CACHE_EXPIRED;

      break;

    case NGX_DECLINED:

      if ((size_t) (u->buffer.end - u->buffer.start) < u->conf->buffer_size) {
        u->buffer.start = NULL;

      } else {
        u->buffer.pos = u->buffer.start + c->header_start;
        u->buffer.last = u->buffer.pos;
      }

      break;

    case NGX_HTTP_CACHE_SCARCE:

      u->cacheable = 0;

      break;

    case NGX_AGAIN:

      return NGX_BUSY;

    case NGX_ERROR:

      return NGX_ERROR;

    default:

      /* cached NGX_HTTP_BAD_GATEWAY, NGX_HTTP_GATEWAY_TIME_OUT, etc. */

      u->cache_status = NGX_HTTP_CACHE_HIT;

      return rc;
  }

  r->cached = 0;

  return NGX_DECLINED;
}


static ngx_int_t
ngx_http_upstream_cache_send(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_int_t          rc;
  ngx_http_cache_t  *c;

  r->cached = 1;
  c = r->cache;

  if (c->header_start == c->body_start) {
    r->http_version = NGX_HTTP_VERSION_9;
    return ngx_http_cache_send(r);
  }

  /* TODO: cache stack */

  u->buffer = *c->buf;
  u->buffer.pos += c->header_start;

  ngx_memzero(&u->headers_in, sizeof(ngx_http_upstream_headers_in_t));
  u->headers_in.content_length_n = -1;

  if (ngx_list_init(&u->headers_in.headers, r->pool, 8,
                    sizeof(ngx_table_elt_t))
      != NGX_OK)
  {
    return NGX_ERROR;
  }

  rc = u->process_header(r);

  if (rc == NGX_OK) {

    if (ngx_http_upstream_process_headers(r, u) != NGX_OK) {
      return NGX_DONE;
    }

    return ngx_http_cache_send(r);
  }

  if (rc == NGX_ERROR) {
    return NGX_ERROR;
  }

  /* rc == NGX_HTTP_UPSTREAM_INVALID_HEADER */

  /* TODO: delete file */

  return rc;
}

#endif


static void
ngx_http_upstream_resolve_handler(ngx_resolver_ctx_t *ctx)
{
  ngx_http_request_t            *r;
  ngx_http_upstream_t           *u;
  ngx_http_upstream_resolved_t  *ur;

  r = ctx->data;

  u = r->upstream;
  ur = u->resolved;

  if (ctx->state) {
    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                  "%V could not be resolved (%i: %s)",
                  &ctx->name, ctx->state,
                  ngx_resolver_strerror(ctx->state));

    ngx_http_upstream_finalize_request(r, u, NGX_HTTP_BAD_GATEWAY);
    return;
  }

  ur->naddrs = ctx->naddrs;
  ur->addrs = ctx->addrs;

#if (NGX_DEBUG)
  {
    in_addr_t   addr;
    ngx_uint_t  i;

    for (i = 0; i < ctx->naddrs; i++) {
      addr = ntohl(ur->addrs[i]);

      ngx_log_debug4(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                     "name was resolved to %ud.%ud.%ud.%ud",
                     (addr >> 24) & 0xff, (addr >> 16) & 0xff,
                     (addr >> 8) & 0xff, addr & 0xff);
    }
  }
#endif

  if (ngx_http_upstream_create_round_robin_peer(r, ur) != NGX_OK) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  ngx_resolve_name_done(ctx);
  ur->ctx = NULL;

  ngx_http_upstream_connect(r, u);
}


static void
ngx_http_upstream_handler(ngx_event_t *ev)
{
  ngx_connection_t     *c;
  ngx_http_request_t   *r;
  ngx_http_log_ctx_t   *ctx;
  ngx_http_upstream_t  *u;

  c = ev->data;
  r = c->data;

  u = r->upstream;
  c = r->connection;

  ctx = c->log->data;
  ctx->current_request = r;

  ngx_log_debug2(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream request: \"%V?%V\"", &r->uri, &r->args);

  if (ev->write) {
    u->write_event_handler(r, u);

  } else {
    u->read_event_handler(r, u);
  }

  ngx_http_run_posted_requests(c);
}


static void
ngx_http_upstream_rd_check_broken_connection(ngx_http_request_t *r)
{
  ngx_http_upstream_check_broken_connection(r, r->connection->read);
}


static void
ngx_http_upstream_wr_check_broken_connection(ngx_http_request_t *r)
{
  ngx_http_upstream_check_broken_connection(r, r->connection->write);
}


static void
ngx_http_upstream_check_broken_connection(ngx_http_request_t *r,
                                          ngx_event_t *ev)
{
  int                  n;
  char                 buf[1];
  ngx_err_t            err;
  ngx_int_t            event;
  ngx_connection_t     *c;
  ngx_http_upstream_t  *u;

  ngx_log_debug2(NGX_LOG_DEBUG_HTTP, ev->log, 0,
                 "http upstream check client, write event:%d, \"%V\"",
                 ev->write, &r->uri);

  c = r->connection;
  u = r->upstream;

  if (c->error) {
    if ((ngx_event_flags & NGX_USE_LEVEL_EVENT) && ev->active) {

      event = ev->write ? NGX_WRITE_EVENT : NGX_READ_EVENT;

      if (ngx_del_event(ev, event, 0) != NGX_OK) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
      }
    }

    if (!u->cacheable) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_CLIENT_CLOSED_REQUEST);
    }

    return;
  }

#if (NGX_HAVE_KQUEUE)

  if (ngx_event_flags & NGX_USE_KQUEUE_EVENT) {

    if (!ev->pending_eof) {
      return;
    }

    ev->eof = 1;
    c->error = 1;

    if (ev->kq_errno) {
      ev->error = 1;
    }

    if (!u->cacheable && u->peer.connection) {
      ngx_log_error(NGX_LOG_INFO, ev->log, ev->kq_errno,
                    "kevent() reported that client prematurely closed "
                    "connection, so upstream connection is closed too");
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_CLIENT_CLOSED_REQUEST);
      return;
    }

    ngx_log_error(NGX_LOG_INFO, ev->log, ev->kq_errno,
                  "kevent() reported that client prematurely closed "
                  "connection");

    if (u->peer.connection == NULL) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_CLIENT_CLOSED_REQUEST);
    }

    return;
  }

#endif

  n = recv(c->fd, buf, 1, MSG_PEEK);

  err = ngx_socket_errno;

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, ev->log, err,
                 "http upstream recv(): %d", n);

  if (ev->write && (n >= 0 || err == NGX_EAGAIN)) {
    return;
  }

  if ((ngx_event_flags & NGX_USE_LEVEL_EVENT) && ev->active) {

    event = ev->write ? NGX_WRITE_EVENT : NGX_READ_EVENT;

    if (ngx_del_event(ev, event, 0) != NGX_OK) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }
  }

  if (n > 0) {
    return;
  }

  if (n == -1) {
    if (err == NGX_EAGAIN) {
      return;
    }

    ev->error = 1;

  } else { /* n == 0 */
    err = 0;
  }

  ev->eof = 1;
  c->error = 1;

  if (!u->cacheable && u->peer.connection) {
    ngx_log_error(NGX_LOG_INFO, ev->log, err,
                  "client prematurely closed connection, "
                  "so upstream connection is closed too");
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_CLIENT_CLOSED_REQUEST);
    return;
  }

  ngx_log_error(NGX_LOG_INFO, ev->log, err,
                "client prematurely closed connection");

  if (u->peer.connection == NULL) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_CLIENT_CLOSED_REQUEST);
  }
}


static void
ngx_http_upstream_connect(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_int_t          rc;
  ngx_time_t        *tp;
  ngx_connection_t  *c;

  r->connection->log->action = "connecting to upstream";

  r->connection->single_connection = 0;

  if (u->state && u->state->response_sec) {
    tp = ngx_timeofday();
    u->state->response_sec = tp->sec - u->state->response_sec;
    u->state->response_msec = tp->msec - u->state->response_msec;
  }

  u->state = ngx_array_push(r->upstream_states);
  if (u->state == NULL) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  ngx_memzero(u->state, sizeof(ngx_http_upstream_state_t));

  tp = ngx_timeofday();
  u->state->response_sec = tp->sec;
  u->state->response_msec = tp->msec;

  rc = ngx_event_connect_peer(&u->peer);

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "http upstream connect: %i", rc);

  if (rc == NGX_ERROR) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  u->state->peer = u->peer.name;

  if (rc == NGX_BUSY) {
    ngx_log_error(NGX_LOG_ERR, r->connection->log, 0, "no live upstreams");
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_NOLIVE);
    return;
  }

  if (rc == NGX_DECLINED) {
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
    return;
  }

  /* rc == NGX_OK || rc == NGX_AGAIN */

  c = u->peer.connection;

  c->data = r;

  c->write->handler = ngx_http_upstream_handler;
  c->read->handler = ngx_http_upstream_handler;

  u->write_event_handler = ngx_http_upstream_send_request_handler;
  u->read_event_handler = ngx_http_upstream_process_header;

  c->sendfile &= r->connection->sendfile;
  u->output.sendfile = c->sendfile;

  if (c->pool == NULL) {

    /* we need separate pool here to be able to cache SSL connections */

    c->pool = ngx_create_pool(128, r->connection->log);
    if (c->pool == NULL) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }
  }

  c->log = r->connection->log;
  c->pool->log = c->log;
  c->read->log = c->log;
  c->write->log = c->log;

  /* init or reinit the ngx_output_chain() and ngx_chain_writer() contexts */

  u->writer.out = NULL;
  u->writer.last = &u->writer.out;
  u->writer.connection = c;
  u->writer.limit = 0;

  if (u->request_sent) {
    if (ngx_http_upstream_reinit(r, u) != NGX_OK) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }
  }

  if (r->request_body
      && r->request_body->buf
      && r->request_body->temp_file
      && r == r->main)
  {
    /*
     * the r->request_body->buf can be reused for one request only,
     * the subrequests should allocate their own temporay bufs
     */

    u->output.free = ngx_alloc_chain_link(r->pool);
    if (u->output.free == NULL) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    u->output.free->buf = r->request_body->buf;
    u->output.free->next = NULL;
    u->output.allocated = 1;

    r->request_body->buf->pos = r->request_body->buf->start;
    r->request_body->buf->last = r->request_body->buf->start;
    r->request_body->buf->tag = u->output.tag;
  }

  u->request_sent = 0;

  if (rc == NGX_AGAIN) {
    ngx_add_timer(c->write, u->conf->connect_timeout);
    return;
  }

#if (NGX_HTTP_SSL)

  if (u->ssl && c->ssl == NULL) {
    ngx_http_upstream_ssl_init_connection(r, u, c);
    return;
  }

#endif

  ngx_http_upstream_send_request(r, u);
}


#if (NGX_HTTP_SSL)

static void
ngx_http_upstream_ssl_init_connection(ngx_http_request_t *r,
                                      ngx_http_upstream_t *u, ngx_connection_t *c)
{
  ngx_int_t   rc;

  if (ngx_ssl_create_connection(u->conf->ssl, c,
                                NGX_SSL_BUFFER|NGX_SSL_CLIENT)
      != NGX_OK)
  {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  c->sendfile = 0;
  u->output.sendfile = 0;

  if (u->conf->ssl_session_reuse) {
    if (u->peer.set_session(&u->peer, u->peer.data) != NGX_OK) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }
  }

  r->connection->log->action = "SSL handshaking to upstream";

  rc = ngx_ssl_handshake(c);

  if (rc == NGX_AGAIN) {
    c->ssl->handler = ngx_http_upstream_ssl_handshake;
    return;
  }

  ngx_http_upstream_ssl_handshake(c);
}


static void
ngx_http_upstream_ssl_handshake(ngx_connection_t *c)
{
  ngx_http_request_t   *r;
  ngx_http_upstream_t  *u;

  r = c->data;
  u = r->upstream;

  if (c->ssl->handshaked) {

    if (u->conf->ssl_session_reuse) {
      u->peer.save_session(&u->peer, u->peer.data);
    }

    c->write->handler = ngx_http_upstream_handler;
    c->read->handler = ngx_http_upstream_handler;

    ngx_http_upstream_send_request(r, u);

    return;
  }

  ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);

}

#endif


static ngx_int_t
ngx_http_upstream_reinit(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_chain_t  *cl;

  if (u->reinit_request(r) != NGX_OK) {
    return NGX_ERROR;
  }

  u->keepalive = 0;

  ngx_memzero(&u->headers_in, sizeof(ngx_http_upstream_headers_in_t));
  u->headers_in.content_length_n = -1;

  if (ngx_list_init(&u->headers_in.headers, r->pool, 8,
                    sizeof(ngx_table_elt_t))
      != NGX_OK)
  {
    return NGX_ERROR;
  }

  /* reinit the request chain */

  for (cl = u->request_bufs; cl; cl = cl->next) {
    cl->buf->pos = cl->buf->start;
    cl->buf->file_pos = 0;
  }

  /* reinit the subrequest's ngx_output_chain() context */

  if (r->request_body && r->request_body->temp_file
      && r != r->main && u->output.buf)
  {
    u->output.free = ngx_alloc_chain_link(r->pool);
    if (u->output.free == NULL) {
      return NGX_ERROR;
    }

    u->output.free->buf = u->output.buf;
    u->output.free->next = NULL;

    u->output.buf->pos = u->output.buf->start;
    u->output.buf->last = u->output.buf->start;
  }

  u->output.buf = NULL;
  u->output.in = NULL;
  u->output.busy = NULL;

  /* reinit u->buffer */

  u->buffer.pos = u->buffer.start;

#if (NGX_HTTP_CACHE)

  if (r->cache) {
    u->buffer.pos += r->cache->header_start;
  }

#endif

  u->buffer.last = u->buffer.pos;

  return NGX_OK;
}


static void
ngx_http_upstream_send_request(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_int_t          rc;
  ngx_connection_t  *c;

  c = u->peer.connection;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream send request");

  if (!u->request_sent && ngx_http_upstream_test_connect(c) != NGX_OK) {
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
    return;
  }

  c->log->action = "sending request to upstream";

  rc = ngx_output_chain(&u->output, u->request_sent ? NULL : u->request_bufs);

  u->request_sent = 1;

  if (rc == NGX_ERROR) {
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
    return;
  }

  if (c->write->timer_set) {
    ngx_del_timer(c->write);
  }

  if (rc == NGX_AGAIN) {
    ngx_add_timer(c->write, u->conf->send_timeout);

    if (ngx_handle_write_event(c->write, u->conf->send_lowat) != NGX_OK) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    return;
  }

  /* rc == NGX_OK */

  if (c->tcp_nopush == NGX_TCP_NOPUSH_SET) {
    if (ngx_tcp_push(c->fd) == NGX_ERROR) {
      ngx_log_error(NGX_LOG_CRIT, c->log, ngx_socket_errno,
                    ngx_tcp_push_n " failed");
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    c->tcp_nopush = NGX_TCP_NOPUSH_UNSET;
  }

  ngx_add_timer(c->read, u->conf->read_timeout);

#if 1
  if (c->read->ready) {

    /* post aio operation */

    /*
     * TODO comment
     * although we can post aio operation just in the end
     * of ngx_http_upstream_connect() CHECK IT !!!
     * it's better to do here because we postpone header buffer allocation
     */

    ngx_http_upstream_process_header(r, u);
    return;
  }
#endif

  u->write_event_handler = ngx_http_upstream_dummy_handler;

  if (ngx_handle_write_event(c->write, 0) != NGX_OK) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }
}


static void
ngx_http_upstream_send_request_handler(ngx_http_request_t *r,
                                       ngx_http_upstream_t *u)
{
  ngx_connection_t  *c;

  c = u->peer.connection;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "http upstream send request handler");

  if (c->write->timedout) {
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_TIMEOUT);
    return;
  }

#if (NGX_HTTP_SSL)

  if (u->ssl && c->ssl == NULL) {
    ngx_http_upstream_ssl_init_connection(r, u, c);
    return;
  }

#endif

  if (u->header_sent) {
    u->write_event_handler = ngx_http_upstream_dummy_handler;

    (void) ngx_handle_write_event(c->write, 0);

    return;
  }

  ngx_http_upstream_send_request(r, u);
}


static void
ngx_http_upstream_process_header(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ssize_t            n;
  ngx_int_t          rc;
  ngx_connection_t  *c;

  c = u->peer.connection;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream process header");

  c->log->action = "reading response header from upstream";

  if (c->read->timedout) {
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_TIMEOUT);
    return;
  }

  if (!u->request_sent && ngx_http_upstream_test_connect(c) != NGX_OK) {
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
    return;
  }

  if (u->buffer.start == NULL) {
    u->buffer.start = ngx_palloc(r->pool, u->conf->buffer_size);
    if (u->buffer.start == NULL) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

    u->buffer.pos = u->buffer.start;
    u->buffer.last = u->buffer.start;
    u->buffer.end = u->buffer.start + u->conf->buffer_size;
    u->buffer.temporary = 1;

    u->buffer.tag = u->output.tag;

    if (ngx_list_init(&u->headers_in.headers, r->pool, 8,
                      sizeof(ngx_table_elt_t))
        != NGX_OK)
    {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return;
    }

#if (NGX_HTTP_CACHE)

    if (r->cache) {
      u->buffer.pos += r->cache->header_start;
      u->buffer.last = u->buffer.pos;
    }
#endif
  }

  for ( ;; ) {

    n = c->recv(c, u->buffer.last, u->buffer.end - u->buffer.last);

    if (n == NGX_AGAIN) {
#if 0
      ngx_add_timer(rev, u->read_timeout);
#endif

      if (ngx_handle_read_event(c->read, 0) != NGX_OK) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return;
      }

      return;
    }

    if (n == 0) {
      ngx_log_error(NGX_LOG_ERR, c->log, 0,
                    "upstream prematurely closed connection");
    }

    if (n == NGX_ERROR || n == 0) {
      ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_ERROR);
      return;
    }

    u->buffer.last += n;

#if 0
    u->valid_header_in = 0;

    u->peer.cached = 0;
#endif

    rc = u->process_header(r);

    if (rc == NGX_AGAIN) {

      if (u->buffer.last == u->buffer.end) {
        ngx_log_error(NGX_LOG_ERR, c->log, 0,
                      "upstream sent too big header");

        ngx_http_upstream_next(r, u,
                               NGX_HTTP_UPSTREAM_FT_INVALID_HEADER);
        return;
      }

      continue;
    }

    break;
  }

  if (rc == NGX_HTTP_UPSTREAM_INVALID_HEADER) {
    ngx_http_upstream_next(r, u, NGX_HTTP_UPSTREAM_FT_INVALID_HEADER);
    return;
  }

  if (rc == NGX_ERROR) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  /* rc == NGX_OK */

  if (u->headers_in.status_n > NGX_HTTP_SPECIAL_RESPONSE) {

    if (r->subrequest_in_memory) {
      u->buffer.last = u->buffer.pos;
    }

    if (ngx_http_upstream_test_next(r, u) == NGX_OK) {
      return;
    }

    if (ngx_http_upstream_intercept_errors(r, u) == NGX_OK) {
      return;
    }
  }

  if (ngx_http_upstream_process_headers(r, u) != NGX_OK) {
    return;
  }

  if (!r->subrequest_in_memory) {
    ngx_http_upstream_send_response(r, u);
    return;
  }

  /* subrequest content in memory */

  if (u->input_filter == NULL) {
    u->input_filter_init = ngx_http_upstream_non_buffered_filter_init;
    u->input_filter = ngx_http_upstream_non_buffered_filter;
    u->input_filter_ctx = r;
  }

  if (u->input_filter_init(u->input_filter_ctx) == NGX_ERROR) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_INTERNAL_SERVER_ERROR);
    return;
  }

  n = u->buffer.last - u->buffer.pos;

  if (n) {
    u->buffer.last -= n;

    u->state->response_length += n;

    if (u->input_filter(u->input_filter_ctx, n) == NGX_ERROR) {
      ngx_http_upstream_finalize_request(r, u, NGX_ERROR);
      return;
    }

    if (u->length == 0) {
      ngx_http_upstream_finalize_request(r, u, 0);
      return;
    }
  }

  u->read_event_handler = ngx_http_upstream_process_body_in_memory;

  ngx_http_upstream_process_body_in_memory(r, u);
}


static ngx_int_t
ngx_http_upstream_test_next(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_uint_t                 status;
  ngx_http_upstream_next_t  *un;

  status = u->headers_in.status_n;

  for (un = ngx_http_upstream_next_errors; un->status; un++) {

    if (status != un->status) {
      continue;
    }

    if (u->peer.tries > 1 && (u->conf->next_upstream & un->mask)) {
      ngx_http_upstream_next(r, u, un->mask);
      return NGX_OK;
    }

#if (NGX_HTTP_CACHE)

    if (u->cache_status == NGX_HTTP_CACHE_EXPIRED
        && (u->conf->cache_use_stale & un->mask))
    {
      ngx_int_t  rc;

      rc = u->reinit_request(r);

      if (rc == NGX_OK) {
        u->cache_status = NGX_HTTP_CACHE_STALE;
        rc = ngx_http_upstream_cache_send(r, u);
      }

      ngx_http_upstream_finalize_request(r, u, rc);
      return NGX_OK;
    }

#endif
  }

  return NGX_DECLINED;
}


static ngx_int_t
ngx_http_upstream_intercept_errors(ngx_http_request_t *r,
                                   ngx_http_upstream_t *u)
{
  ngx_int_t                  status;
  ngx_uint_t                 i;
  ngx_table_elt_t           *h;
  ngx_http_err_page_t       *err_page;
  ngx_http_core_loc_conf_t  *clcf;

  status = u->headers_in.status_n;

  if (status == NGX_HTTP_NOT_FOUND && u->conf->intercept_404) {
    ngx_http_upstream_finalize_request(r, u, NGX_HTTP_NOT_FOUND);
    return NGX_OK;
  }

  if (!u->conf->intercept_errors) {
    return NGX_DECLINED;
  }

  clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

  if (clcf->error_pages == NULL) {
    return NGX_DECLINED;
  }

  err_page = clcf->error_pages->elts;
  for (i = 0; i < clcf->error_pages->nelts; i++) {

    if (err_page[i].status == status) {

      if (status == NGX_HTTP_UNAUTHORIZED
          && u->headers_in.www_authenticate)
      {
        h = ngx_list_push(&r->headers_out.headers);

        if (h == NULL) {
          ngx_http_upstream_finalize_request(r, u,
                                             NGX_HTTP_INTERNAL_SERVER_ERROR);
          return NGX_OK;
        }

        *h = *u->headers_in.www_authenticate;

        r->headers_out.www_authenticate = h;
      }

#if (NGX_HTTP_CACHE)

      if (r->cache) {
        time_t  valid;

        valid = ngx_http_file_cache_valid(u->conf->cache_valid, status);

        if (valid) {
          r->cache->valid_sec = ngx_time() + valid;
          r->cache->error = status;
        }

        ngx_http_file_cache_free(r->cache, u->pipe->temp_file);
      }
#endif
      ngx_http_upstream_finalize_request(r, u, status);

      return NGX_OK;
    }
  }

  return NGX_DECLINED;
}


static ngx_int_t
ngx_http_upstream_test_connect(ngx_connection_t *c)
{
  int        err;
  socklen_t  len;

#if (NGX_HAVE_KQUEUE)

  if (ngx_event_flags & NGX_USE_KQUEUE_EVENT)  {
    if (c->write->pending_eof) {
      c->log->action = "connecting to upstream";
      (void) ngx_connection_error(c, c->write->kq_errno,
                                  "kevent() reported that connect() failed");
      return NGX_ERROR;
    }

  } else
#endif
  {
    err = 0;
    len = sizeof(int);

    /*
     * BSDs and Linux return 0 and set a pending error in err
     * Solaris returns -1 and sets errno
     */

    if (getsockopt(c->fd, SOL_SOCKET, SO_ERROR, (void *) &err, &len)
        == -1)
    {
      err = ngx_errno;
    }

    if (err) {
      c->log->action = "connecting to upstream";
      (void) ngx_connection_error(c, err, "connect() failed");
      return NGX_ERROR;
    }
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_headers(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_str_t                      *uri, args;
  ngx_uint_t                      i, flags;
  ngx_list_part_t                *part;
  ngx_table_elt_t                *h;
  ngx_http_upstream_header_t     *hh;
  ngx_http_upstream_main_conf_t  *umcf;

  umcf = ngx_http_get_module_main_conf(r, ngx_http_upstream_module);

  if (u->headers_in.x_accel_redirect
      && !(u->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_XA_REDIRECT))
  {
    ngx_http_upstream_finalize_request(r, u, NGX_DECLINED);

    part = &u->headers_in.headers.part;
    h = part->elts;

    for (i = 0; /* void */; i++) {

      if (i >= part->nelts) {
        if (part->next == NULL) {
          break;
        }

        part = part->next;
        h = part->elts;
        i = 0;
      }

      hh = ngx_hash_find(&umcf->headers_in_hash, h[i].hash,
                         h[i].lowcase_key, h[i].key.len);

      if (hh && hh->redirect) {
        if (hh->copy_handler(r, &h[i], hh->conf) != NGX_OK) {
          ngx_http_finalize_request(r,
                                    NGX_HTTP_INTERNAL_SERVER_ERROR);
          return NGX_DONE;
        }
      }
    }

    uri = &u->headers_in.x_accel_redirect->value;
    ngx_str_null(&args);
    flags = NGX_HTTP_LOG_UNSAFE;

    if (ngx_http_parse_unsafe_uri(r, uri, &args, &flags) != NGX_OK) {
      ngx_http_finalize_request(r, NGX_HTTP_NOT_FOUND);
      return NGX_DONE;
    }

    if (r->method != NGX_HTTP_HEAD) {
      r->method = NGX_HTTP_GET;
    }

    ngx_http_internal_redirect(r, uri, &args);
    ngx_http_finalize_request(r, NGX_DONE);
    return NGX_DONE;
  }

  part = &u->headers_in.headers.part;
  h = part->elts;

  for (i = 0; /* void */; i++) {

    if (i >= part->nelts) {
      if (part->next == NULL) {
        break;
      }

      part = part->next;
      h = part->elts;
      i = 0;
    }

    if (ngx_hash_find(&u->conf->hide_headers_hash, h[i].hash,
                      h[i].lowcase_key, h[i].key.len))
    {
      continue;
    }

    hh = ngx_hash_find(&umcf->headers_in_hash, h[i].hash,
                       h[i].lowcase_key, h[i].key.len);

    if (hh) {
      if (hh->copy_handler(r, &h[i], hh->conf) != NGX_OK) {
        ngx_http_upstream_finalize_request(r, u,
                                           NGX_HTTP_INTERNAL_SERVER_ERROR);
        return NGX_DONE;
      }

      continue;
    }

    if (ngx_http_upstream_copy_header_line(r, &h[i], 0) != NGX_OK) {
      ngx_http_upstream_finalize_request(r, u,
                                         NGX_HTTP_INTERNAL_SERVER_ERROR);
      return NGX_DONE;
    }
  }

  if (r->headers_out.server && r->headers_out.server->value.data == NULL) {
    r->headers_out.server->hash = 0;
  }

  if (r->headers_out.date && r->headers_out.date->value.data == NULL) {
    r->headers_out.date->hash = 0;
  }

  r->headers_out.status = u->headers_in.status_n;
  r->headers_out.status_line = u->headers_in.status_line;

  r->headers_out.content_length_n = u->headers_in.content_length_n;

  u->length = u->headers_in.content_length_n;

  return NGX_OK;
}


static void
ngx_http_upstream_process_body_in_memory(ngx_http_request_t *r,
                                         ngx_http_upstream_t *u)
{
  size_t             size;
  ssize_t            n;
  ngx_buf_t         *b;
  ngx_event_t       *rev;
  ngx_connection_t  *c;

  c = u->peer.connection;
  rev = c->read;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream process body on memory");

  if (rev->timedout) {
    ngx_connection_error(c, NGX_ETIMEDOUT, "upstream timed out");
    ngx_http_upstream_finalize_request(r, u, NGX_ETIMEDOUT);
    return;
  }

  b = &u->buffer;

  for ( ;; ) {

    size = b->end - b->last;

    if (size == 0) {
      ngx_log_error(NGX_LOG_ALERT, c->log, 0,
                    "upstream buffer is too small to read response");
      ngx_http_upstream_finalize_request(r, u, NGX_ERROR);
      return;
    }

    n = c->recv(c, b->last, size);

    if (n == NGX_AGAIN) {
      break;
    }

    if (n == 0 || n == NGX_ERROR) {
      ngx_http_upstream_finalize_request(r, u, n);
      return;
    }

    u->state->response_length += n;

    if (u->input_filter(u->input_filter_ctx, n) == NGX_ERROR) {
      ngx_http_upstream_finalize_request(r, u, NGX_ERROR);
      return;
    }

    if (!rev->ready) {
      break;
    }
  }

  if (u->length == 0) {
    ngx_http_upstream_finalize_request(r, u, 0);
    return;
  }

  if (ngx_handle_read_event(rev, 0) != NGX_OK) {
    ngx_http_upstream_finalize_request(r, u, NGX_ERROR);
    return;
  }

  if (rev->active) {
    ngx_add_timer(rev, u->conf->read_timeout);

  } else if (rev->timer_set) {
    ngx_del_timer(rev);
  }
}


static void
ngx_http_upstream_send_response(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  int                        tcp_nodelay;
  ssize_t                    n;
  ngx_int_t                  rc;
  ngx_event_pipe_t          *p;
  ngx_connection_t          *c;
  ngx_http_core_loc_conf_t  *clcf;

  rc = ngx_http_send_header(r);

  if (rc == NGX_ERROR || rc > NGX_OK || r->post_action) {
    ngx_http_upstream_finalize_request(r, u, rc);
    return;
  }

  c = r->connection;

  if (r->header_only) {

    if (u->cacheable || u->store) {

      if (ngx_shutdown_socket(c->fd, NGX_WRITE_SHUTDOWN) == -1) {
        ngx_connection_error(c, ngx_socket_errno,
                             ngx_shutdown_socket_n " failed");
      }

      r->read_event_handler = ngx_http_request_empty_handler;
      r->write_event_handler = ngx_http_request_empty_handler;
      c->error = 1;

    } else {
      ngx_http_upstream_finalize_request(r, u, rc);
      return;
    }
  }

  u->header_sent = 1;

  if (r->request_body && r->request_body->temp_file) {
    ngx_pool_run_cleanup_file(r->pool, r->request_body->temp_file->file.fd);
    r->request_body->temp_file->file.fd = NGX_INVALID_FILE;
  }

  clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

  if (!u->buffering) {

    if (u->input_filter == NULL) {
      u->input_filter_init = ngx_http_upstream_non_buffered_filter_init;
      u->input_filter = ngx_http_upstream_non_buffered_filter;
      u->input_filter_ctx = r;
    }

    u->read_event_handler = ngx_http_upstream_process_non_buffered_upstream;
    r->write_event_handler =
        ngx_http_upstream_process_non_buffered_downstream;

    r->limit_rate = 0;

    if (u->input_filter_init(u->input_filter_ctx) == NGX_ERROR) {
      ngx_http_upstream_finalize_request(r, u, 0);
      return;
    }

    if (clcf->tcp_nodelay && c->tcp_nodelay == NGX_TCP_NODELAY_UNSET) {
      ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0, "tcp_nodelay");

      tcp_nodelay = 1;

      if (setsockopt(c->fd, IPPROTO_TCP, TCP_NODELAY,
                     (const void *) &tcp_nodelay, sizeof(int)) == -1)
      {
        ngx_connection_error(c, ngx_socket_errno,
                             "setsockopt(TCP_NODELAY) failed");
        ngx_http_upstream_finalize_request(r, u, 0);
        return;
      }

      c->tcp_nodelay = NGX_TCP_NODELAY_SET;
    }

    n = u->buffer.last - u->buffer.pos;

    if (n) {
      u->buffer.last = u->buffer.pos;

      u->state->response_length += n;

      if (u->input_filter(u->input_filter_ctx, n) == NGX_ERROR) {
        ngx_http_upstream_finalize_request(r, u, 0);
        return;
      }

      ngx_http_upstream_process_non_buffered_downstream(r);

    } else {
      u->buffer.pos = u->buffer.start;
      u->buffer.last = u->buffer.start;

      if (ngx_http_send_special(r, NGX_HTTP_FLUSH) == NGX_ERROR) {
        ngx_http_upstream_finalize_request(r, u, 0);
        return;
      }

      if (u->peer.connection->read->ready || u->length == 0) {
        ngx_http_upstream_process_non_buffered_upstream(r, u);
      }
    }

    return;
  }

  /* TODO: preallocate event_pipe bufs, look "Content-Length" */

#if (NGX_HTTP_CACHE)

  if (r->cache && r->cache->file.fd != NGX_INVALID_FILE) {
    ngx_pool_run_cleanup_file(r->pool, r->cache->file.fd);
    r->cache->file.fd = NGX_INVALID_FILE;
  }

  switch (ngx_http_test_predicates(r, u->conf->no_cache)) {

    case NGX_ERROR:
      ngx_http_upstream_finalize_request(r, u, 0);
      return;

    case NGX_DECLINED:
      u->cacheable = 0;
      break;

    default: /* NGX_OK */

      if (u->cache_status == NGX_HTTP_CACHE_BYPASS) {

        r->cache->min_uses = u->conf->cache_min_uses;
        r->cache->body_start = u->conf->buffer_size;
        r->cache->file_cache = u->conf->cache->data;

        if (ngx_http_file_cache_create(r) != NGX_OK) {
          ngx_http_upstream_finalize_request(r, u, 0);
          return;
        }
      }

      break;
  }

  if (u->cacheable) {
    time_t  now, valid;

    now = ngx_time();

    valid = r->cache->valid_sec;

    if (valid == 0) {
      valid = ngx_http_file_cache_valid(u->conf->cache_valid,
                                        u->headers_in.status_n);
      if (valid) {
        r->cache->valid_sec = now + valid;
      }
    }

    if (valid) {
      r->cache->last_modified = r->headers_out.last_modified_time;
      r->cache->date = now;
      r->cache->body_start = (u_short) (u->buffer.pos - u->buffer.start);

      ngx_http_file_cache_set_header(r, u->buffer.start);

    } else {
      u->cacheable = 0;
      r->headers_out.last_modified_time = -1;
    }
  }

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http cacheable: %d", u->cacheable);

  if (u->cacheable == 0 && r->cache) {
    ngx_http_file_cache_free(r->cache, u->pipe->temp_file);
  }

#endif

  p = u->pipe;

  p->output_filter = (ngx_event_pipe_output_filter_pt) ngx_http_output_filter;
  p->output_ctx = r;
  p->tag = u->output.tag;
  p->bufs = u->conf->bufs;
  p->busy_size = u->conf->busy_buffers_size;
  p->upstream = u->peer.connection;
  p->downstream = c;
  p->pool = r->pool;
  p->log = c->log;

  p->cacheable = u->cacheable || u->store;

  p->temp_file = ngx_pcalloc(r->pool, sizeof(ngx_temp_file_t));
  if (p->temp_file == NULL) {
    ngx_http_upstream_finalize_request(r, u, 0);
    return;
  }

  p->temp_file->file.fd = NGX_INVALID_FILE;
  p->temp_file->file.log = c->log;
  p->temp_file->path = u->conf->temp_path;
  p->temp_file->pool = r->pool;

  if (p->cacheable) {
    p->temp_file->persistent = 1;

  } else {
    p->temp_file->log_level = NGX_LOG_WARN;
    p->temp_file->warn = "an upstream response is buffered "
        "to a temporary file";
  }

  p->max_temp_file_size = u->conf->max_temp_file_size;
  p->temp_file_write_size = u->conf->temp_file_write_size;

  p->preread_bufs = ngx_alloc_chain_link(r->pool);
  if (p->preread_bufs == NULL) {
    ngx_http_upstream_finalize_request(r, u, 0);
    return;
  }

  p->preread_bufs->buf = &u->buffer;
  p->preread_bufs->next = NULL;
  u->buffer.recycled = 1;

  p->preread_size = u->buffer.last - u->buffer.pos;

  if (u->cacheable) {

    p->buf_to_file = ngx_calloc_buf(r->pool);
    if (p->buf_to_file == NULL) {
      ngx_http_upstream_finalize_request(r, u, 0);
      return;
    }

    p->buf_to_file->pos = u->buffer.start;
    p->buf_to_file->last = u->buffer.pos;
    p->buf_to_file->temporary = 1;
  }

  if (ngx_event_flags & NGX_USE_AIO_EVENT) {
    /* the posted aio operation may currupt a shadow buffer */
    p->single_buf = 1;
  }

  /* TODO: p->free_bufs = 0 if use ngx_create_chain_of_bufs() */
  p->free_bufs = 1;

  /*
   * event_pipe would do u->buffer.last += p->preread_size
   * as though these bytes were read
   */
  u->buffer.last = u->buffer.pos;

  if (u->conf->cyclic_temp_file) {

    /*
     * we need to disable the use of sendfile() if we use cyclic temp file
     * because the writing a new data may interfere with sendfile()
     * that uses the same kernel file pages (at least on FreeBSD)
     */

    p->cyclic_temp_file = 1;
    c->sendfile = 0;

  } else {
    p->cyclic_temp_file = 0;
  }

  p->read_timeout = u->conf->read_timeout;
  p->send_timeout = clcf->send_timeout;
  p->send_lowat = clcf->send_lowat;

  p->length = -1;

  if (u->input_filter_init
      && u->input_filter_init(p->input_ctx) != NGX_OK)
  {
    ngx_http_upstream_finalize_request(r, u, 0);
    return;
  }

  u->read_event_handler = ngx_http_upstream_process_upstream;
  r->write_event_handler = ngx_http_upstream_process_downstream;

  ngx_http_upstream_process_upstream(r, u);
}


static void
ngx_http_upstream_process_non_buffered_downstream(ngx_http_request_t *r)
{
  ngx_event_t          *wev;
  ngx_connection_t     *c;
  ngx_http_upstream_t  *u;

  c = r->connection;
  u = r->upstream;
  wev = c->write;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream process non buffered downstream");

  c->log->action = "sending to client";

  if (wev->timedout) {
    c->timedout = 1;
    ngx_connection_error(c, NGX_ETIMEDOUT, "client timed out");
    ngx_http_upstream_finalize_request(r, u, NGX_HTTP_REQUEST_TIME_OUT);
    return;
  }

  ngx_http_upstream_process_non_buffered_request(r, 1);
}


static void
ngx_http_upstream_process_non_buffered_upstream(ngx_http_request_t *r,
                                                ngx_http_upstream_t *u)
{
  ngx_connection_t  *c;

  c = u->peer.connection;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream process non buffered upstream");

  c->log->action = "reading upstream";

  if (c->read->timedout) {
    ngx_connection_error(c, NGX_ETIMEDOUT, "upstream timed out");
    ngx_http_upstream_finalize_request(r, u, 0);
    return;
  }

  ngx_http_upstream_process_non_buffered_request(r, 0);
}


static void
ngx_http_upstream_process_non_buffered_request(ngx_http_request_t *r,
                                               ngx_uint_t do_write)
{
  size_t                     size;
  ssize_t                    n;
  ngx_buf_t                 *b;
  ngx_int_t                  rc;
  ngx_connection_t          *downstream, *upstream;
  ngx_http_upstream_t       *u;
  ngx_http_core_loc_conf_t  *clcf;

  u = r->upstream;
  downstream = r->connection;
  upstream = u->peer.connection;

  b = &u->buffer;

  do_write = do_write || u->length == 0;

  for ( ;; ) {

    if (do_write) {

      if (u->out_bufs || u->busy_bufs) {
        rc = ngx_http_output_filter(r, u->out_bufs);

        if (rc == NGX_ERROR) {
          ngx_http_upstream_finalize_request(r, u, 0);
          return;
        }

        ngx_chain_update_chains(r->pool, &u->free_bufs, &u->busy_bufs,
                                &u->out_bufs, u->output.tag);
      }

      if (u->busy_bufs == NULL) {

        if (u->length == 0
            || upstream->read->eof
            || upstream->read->error)
        {
          ngx_http_upstream_finalize_request(r, u, 0);
          return;
        }

        b->pos = b->start;
        b->last = b->start;
      }
    }

    size = b->end - b->last;

    if (size && upstream->read->ready) {

      n = upstream->recv(upstream, b->last, size);

      if (n == NGX_AGAIN) {
        break;
      }

      if (n > 0) {
        u->state->response_length += n;

        if (u->input_filter(u->input_filter_ctx, n) == NGX_ERROR) {
          ngx_http_upstream_finalize_request(r, u, 0);
          return;
        }
      }

      do_write = 1;

      continue;
    }

    break;
  }

  clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

  if (downstream->data == r) {
    if (ngx_handle_write_event(downstream->write, clcf->send_lowat)
        != NGX_OK)
    {
      ngx_http_upstream_finalize_request(r, u, 0);
      return;
    }
  }

  if (downstream->write->active && !downstream->write->ready) {
    ngx_add_timer(downstream->write, clcf->send_timeout);

  } else if (downstream->write->timer_set) {
    ngx_del_timer(downstream->write);
  }

  if (ngx_handle_read_event(upstream->read, 0) != NGX_OK) {
    ngx_http_upstream_finalize_request(r, u, 0);
    return;
  }

  if (upstream->read->active && !upstream->read->ready) {
    ngx_add_timer(upstream->read, u->conf->read_timeout);

  } else if (upstream->read->timer_set) {
    ngx_del_timer(upstream->read);
  }
}


static ngx_int_t
ngx_http_upstream_non_buffered_filter_init(void *data)
{
  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_non_buffered_filter(void *data, ssize_t bytes)
{
  ngx_http_request_t  *r = data;

  ngx_buf_t            *b;
  ngx_chain_t          *cl, **ll;
  ngx_http_upstream_t  *u;

  u = r->upstream;

  for (cl = u->out_bufs, ll = &u->out_bufs; cl; cl = cl->next) {
    ll = &cl->next;
  }

  cl = ngx_chain_get_free_buf(r->pool, &u->free_bufs);
  if (cl == NULL) {
    return NGX_ERROR;
  }

  *ll = cl;

  cl->buf->flush = 1;
  cl->buf->memory = 1;

  b = &u->buffer;

  cl->buf->pos = b->last;
  b->last += bytes;
  cl->buf->last = b->last;
  cl->buf->tag = u->output.tag;

  if (u->length == -1) {
    return NGX_OK;
  }

  u->length -= bytes;

  return NGX_OK;
}


static void
ngx_http_upstream_process_downstream(ngx_http_request_t *r)
{
  ngx_event_t          *wev;
  ngx_connection_t     *c;
  ngx_event_pipe_t     *p;
  ngx_http_upstream_t  *u;

  c = r->connection;
  u = r->upstream;
  p = u->pipe;
  wev = c->write;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream process downstream");

  c->log->action = "sending to client";

  if (wev->timedout) {

    if (wev->delayed) {

      wev->timedout = 0;
      wev->delayed = 0;

      if (!wev->ready) {
        ngx_add_timer(wev, p->send_timeout);

        if (ngx_handle_write_event(wev, p->send_lowat) != NGX_OK) {
          ngx_http_upstream_finalize_request(r, u, 0);
        }

        return;
      }

      if (ngx_event_pipe(p, wev->write) == NGX_ABORT) {
        ngx_http_upstream_finalize_request(r, u, 0);
        return;
      }

    } else {
      p->downstream_error = 1;
      c->timedout = 1;
      ngx_connection_error(c, NGX_ETIMEDOUT, "client timed out");
    }

  } else {

    if (wev->delayed) {

      ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                     "http downstream delayed");

      if (ngx_handle_write_event(wev, p->send_lowat) != NGX_OK) {
        ngx_http_upstream_finalize_request(r, u, 0);
      }

      return;
    }

    if (ngx_event_pipe(p, 1) == NGX_ABORT) {
      ngx_http_upstream_finalize_request(r, u, 0);
      return;
    }
  }

  ngx_http_upstream_process_request(r);
}


static void
ngx_http_upstream_process_upstream(ngx_http_request_t *r,
                                   ngx_http_upstream_t *u)
{
  ngx_connection_t  *c;

  c = u->peer.connection;

  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, c->log, 0,
                 "http upstream process upstream");

  c->log->action = "reading upstream";

  if (c->read->timedout) {
    u->pipe->upstream_error = 1;
    ngx_connection_error(c, NGX_ETIMEDOUT, "upstream timed out");

  } else {
    if (ngx_event_pipe(u->pipe, 0) == NGX_ABORT) {
      ngx_http_upstream_finalize_request(r, u, 0);
      return;
    }
  }

  ngx_http_upstream_process_request(r);
}


static void
ngx_http_upstream_process_request(ngx_http_request_t *r)
{
  ngx_temp_file_t      *tf;
  ngx_event_pipe_t     *p;
  ngx_http_upstream_t  *u;

  u = r->upstream;
  p = u->pipe;

  if (u->peer.connection) {

    if (u->store) {

      if (p->upstream_eof || p->upstream_done) {

        tf = u->pipe->temp_file;

        if (u->headers_in.status_n == NGX_HTTP_OK
            && (u->headers_in.content_length_n == -1
                || (u->headers_in.content_length_n == tf->offset)))
        {
          ngx_http_upstream_store(r, u);
          u->store = 0;
        }
      }
    }

#if (NGX_HTTP_CACHE)

    if (u->cacheable) {

      if (p->upstream_done) {
        ngx_http_file_cache_update(r, u->pipe->temp_file);

      } else if (p->upstream_eof) {

        tf = u->pipe->temp_file;

        if (u->headers_in.content_length_n == -1
            || u->headers_in.content_length_n
            == tf->offset - (off_t) r->cache->body_start)
        {
          ngx_http_file_cache_update(r, tf);

        } else {
          ngx_http_file_cache_free(r->cache, tf);
        }

      } else if (p->upstream_error) {
        ngx_http_file_cache_free(r->cache, u->pipe->temp_file);
      }
    }

#endif

    if (p->upstream_done || p->upstream_eof || p->upstream_error) {
      ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                     "http upstream exit: %p", p->out);
#if 0
      ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
#endif
      ngx_http_upstream_finalize_request(r, u, 0);
      return;
    }
  }

  if (p->downstream_error) {
    ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http upstream downstream error");

    if (!u->cacheable && !u->store && u->peer.connection) {
      ngx_http_upstream_finalize_request(r, u, 0);
    }
  }
}


static void
ngx_http_upstream_store(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  size_t                  root;
  time_t                  lm;
  ngx_str_t               path;
  ngx_temp_file_t        *tf;
  ngx_ext_rename_file_t   ext;

  tf = u->pipe->temp_file;

  if (tf->file.fd == NGX_INVALID_FILE) {

    /* create file for empty 200 response */

    tf = ngx_pcalloc(r->pool, sizeof(ngx_temp_file_t));
    if (tf == NULL) {
      return;
    }

    tf->file.fd = NGX_INVALID_FILE;
    tf->file.log = r->connection->log;
    tf->path = u->conf->temp_path;
    tf->pool = r->pool;
    tf->persistent = 1;

    if (ngx_create_temp_file(&tf->file, tf->path, tf->pool,
                             tf->persistent, tf->clean, tf->access)
        != NGX_OK)
    {
      return;
    }

    u->pipe->temp_file = tf;
  }

  ext.access = u->conf->store_access;
  ext.path_access = u->conf->store_access;
  ext.time = -1;
  ext.create_path = 1;
  ext.delete_file = 1;
  ext.log = r->connection->log;

  if (u->headers_in.last_modified) {

    lm = ngx_http_parse_time(u->headers_in.last_modified->value.data,
                             u->headers_in.last_modified->value.len);

    if (lm != NGX_ERROR) {
      ext.time = lm;
      ext.fd = tf->file.fd;
    }
  }

  if (u->conf->store_lengths == NULL) {

    ngx_http_map_uri_to_path(r, &path, &root, 0);

  } else {
    if (ngx_http_script_run(r, &path, u->conf->store_lengths->elts, 0,
                            u->conf->store_values->elts)
        == NULL)
    {
      return;
    }
  }

  path.len--;

  ngx_log_debug2(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "upstream stores \"%s\" to \"%s\"",
                 tf->file.name.data, path.data);

  (void) ngx_ext_rename_file(&tf->file.name, &path, &ext);
}


static void
ngx_http_upstream_dummy_handler(ngx_http_request_t *r, ngx_http_upstream_t *u)
{
  ngx_log_debug0(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "http upstream dummy handler");
}


static void
ngx_http_upstream_next(ngx_http_request_t *r, ngx_http_upstream_t *u,
                       ngx_uint_t ft_type)
{
  ngx_uint_t  status, state;

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "http next upstream, %xi", ft_type);

#if 0
  ngx_http_busy_unlock(u->conf->busy_lock, &u->busy_lock);
#endif

  if (ft_type == NGX_HTTP_UPSTREAM_FT_HTTP_404) {
    state = NGX_PEER_NEXT;
  } else {
    state = NGX_PEER_FAILED;
  }

  if (ft_type != NGX_HTTP_UPSTREAM_FT_NOLIVE) {
    u->peer.free(&u->peer, u->peer.data, state);
  }

  if (ft_type == NGX_HTTP_UPSTREAM_FT_TIMEOUT) {
    ngx_log_error(NGX_LOG_ERR, r->connection->log, NGX_ETIMEDOUT,
                  "upstream timed out");
  }

  if (u->peer.cached && ft_type == NGX_HTTP_UPSTREAM_FT_ERROR) {
    status = 0;

    /* TODO: inform balancer instead */

    u->peer.tries++;

  } else {
    switch(ft_type) {

      case NGX_HTTP_UPSTREAM_FT_TIMEOUT:
        status = NGX_HTTP_GATEWAY_TIME_OUT;
        break;

      case NGX_HTTP_UPSTREAM_FT_HTTP_500:
        status = NGX_HTTP_INTERNAL_SERVER_ERROR;
        break;

      case NGX_HTTP_UPSTREAM_FT_HTTP_404:
        status = NGX_HTTP_NOT_FOUND;
        break;

        /*
         * NGX_HTTP_UPSTREAM_FT_BUSY_LOCK and NGX_HTTP_UPSTREAM_FT_MAX_WAITING
         * never reach here
         */

      default:
        status = NGX_HTTP_BAD_GATEWAY;
    }
  }

  if (r->connection->error) {
    ngx_http_upstream_finalize_request(r, u,
                                       NGX_HTTP_CLIENT_CLOSED_REQUEST);
    return;
  }

  if (status) {
    u->state->status = status;

    if (u->peer.tries == 0 || !(u->conf->next_upstream & ft_type)) {

#if (NGX_HTTP_CACHE)

      if (u->cache_status == NGX_HTTP_CACHE_EXPIRED
          && (u->conf->cache_use_stale & ft_type))
      {
        ngx_int_t  rc;

        rc = u->reinit_request(r);

        if (rc == NGX_OK) {
          u->cache_status = NGX_HTTP_CACHE_STALE;
          rc = ngx_http_upstream_cache_send(r, u);
        }

        ngx_http_upstream_finalize_request(r, u, rc);
        return;
      }
#endif

      ngx_http_upstream_finalize_request(r, u, status);
      return;
    }
  }

  if (u->peer.connection) {
    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "close http upstream connection: %d",
                   u->peer.connection->fd);
#if (NGX_HTTP_SSL)

    if (u->peer.connection->ssl) {
      u->peer.connection->ssl->no_wait_shutdown = 1;
      u->peer.connection->ssl->no_send_shutdown = 1;

      (void) ngx_ssl_shutdown(u->peer.connection);
    }
#endif

    if (u->peer.connection->pool) {
      ngx_destroy_pool(u->peer.connection->pool);
    }

    ngx_close_connection(u->peer.connection);
    u->peer.connection = NULL;
  }

#if 0
  if (u->conf->busy_lock && !u->busy_locked) {
    ngx_http_upstream_busy_lock(p);
    return;
  }
#endif

  ngx_http_upstream_connect(r, u);
}


static void
ngx_http_upstream_cleanup(void *data)
{
  ngx_http_request_t *r = data;

  ngx_http_upstream_t  *u;

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "cleanup http upstream request: \"%V\"", &r->uri);

  u = r->upstream;

  if (u->resolved && u->resolved->ctx) {
    ngx_resolve_name_done(u->resolved->ctx);
    u->resolved->ctx = NULL;
  }

  ngx_http_upstream_finalize_request(r, u, NGX_DONE);
}


static void
ngx_http_upstream_finalize_request(ngx_http_request_t *r,
                                   ngx_http_upstream_t *u, ngx_int_t rc)
{
  ngx_time_t  *tp;

  ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                 "finalize http upstream request: %i", rc);

  if (u->cleanup) {
    *u->cleanup = NULL;
    u->cleanup = NULL;
  }

  if (u->resolved && u->resolved->ctx) {
    ngx_resolve_name_done(u->resolved->ctx);
    u->resolved->ctx = NULL;
  }

  if (u->state && u->state->response_sec) {
    tp = ngx_timeofday();
    u->state->response_sec = tp->sec - u->state->response_sec;
    u->state->response_msec = tp->msec - u->state->response_msec;

    if (u->pipe) {
      u->state->response_length = u->pipe->read_length;
    }
  }

  u->finalize_request(r, rc);

  if (u->peer.free) {
    u->peer.free(&u->peer, u->peer.data, 0);
  }

  if (u->peer.connection) {

#if (NGX_HTTP_SSL)

    /* TODO: do not shutdown persistent connection */

    if (u->peer.connection->ssl) {

      /*
       * We send the "close notify" shutdown alert to the upstream only
       * and do not wait its "close notify" shutdown alert.
       * It is acceptable according to the TLS standard.
       */

      u->peer.connection->ssl->no_wait_shutdown = 1;

      (void) ngx_ssl_shutdown(u->peer.connection);
    }
#endif

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "close http upstream connection: %d",
                   u->peer.connection->fd);

    if (u->peer.connection->pool) {
      ngx_destroy_pool(u->peer.connection->pool);
    }

    ngx_close_connection(u->peer.connection);
  }

  u->peer.connection = NULL;

  if (u->pipe && u->pipe->temp_file) {
    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "http upstream temp fd: %d",
                   u->pipe->temp_file->file.fd);
  }

  if (u->store && u->pipe && u->pipe->temp_file
      && u->pipe->temp_file->file.fd != NGX_INVALID_FILE)
  {
    if (ngx_delete_file(u->pipe->temp_file->file.name.data)
        == NGX_FILE_ERROR)
    {
      ngx_log_error(NGX_LOG_CRIT, r->connection->log, ngx_errno,
                    ngx_delete_file_n " \"%s\" failed",
                    u->pipe->temp_file->file.name.data);
    }
  }

#if (NGX_HTTP_CACHE)

  if (r->cache) {

    if (u->cacheable) {

      if (rc == NGX_HTTP_BAD_GATEWAY || rc == NGX_HTTP_GATEWAY_TIME_OUT) {
        time_t  valid;

        valid = ngx_http_file_cache_valid(u->conf->cache_valid, rc);

        if (valid) {
          r->cache->valid_sec = ngx_time() + valid;
          r->cache->error = rc;
        }
      }
    }

    ngx_http_file_cache_free(r->cache, u->pipe->temp_file);
  }

#endif

  if (u->header_sent
      && rc != NGX_HTTP_REQUEST_TIME_OUT
      && (rc == NGX_ERROR || rc >= NGX_HTTP_SPECIAL_RESPONSE))
  {
    rc = 0;
  }

  if (rc == NGX_DECLINED) {
    return;
  }

  r->connection->log->action = "sending to client";

  if (rc == 0
#if (NGX_HTTP_CACHE)
      && !r->cached
#endif
      )
  {
    rc = ngx_http_send_special(r, NGX_HTTP_LAST);
  }

  ngx_http_finalize_request(r, rc);
}


static ngx_int_t
ngx_http_upstream_process_header_line(ngx_http_request_t *r, ngx_table_elt_t *h,
                                      ngx_uint_t offset)
{
  ngx_table_elt_t  **ph;

  ph = (ngx_table_elt_t **) ((char *) &r->upstream->headers_in + offset);

  if (*ph == NULL) {
    *ph = h;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_ignore_header_line(ngx_http_request_t *r, ngx_table_elt_t *h,
                                     ngx_uint_t offset)
{
  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_content_length(ngx_http_request_t *r,
                                         ngx_table_elt_t *h, ngx_uint_t offset)
{
  ngx_http_upstream_t  *u;

  u = r->upstream;

  u->headers_in.content_length = h;
  u->headers_in.content_length_n = ngx_atoof(h->value.data, h->value.len);

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_set_cookie(ngx_http_request_t *r, ngx_table_elt_t *h,
                                     ngx_uint_t offset)
{
#if (NGX_HTTP_CACHE)
  ngx_http_upstream_t  *u;

  u = r->upstream;

  if (!(u->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_SET_COOKIE)) {
    u->cacheable = 0;
  }
#endif

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_cache_control(ngx_http_request_t *r,
                                        ngx_table_elt_t *h, ngx_uint_t offset)
{
  ngx_array_t          *pa;
  ngx_table_elt_t     **ph;
  ngx_http_upstream_t  *u;

  u = r->upstream;
  pa = &u->headers_in.cache_control;

  if (pa->elts == NULL) {
    if (ngx_array_init(pa, r->pool, 2, sizeof(ngx_table_elt_t *)) != NGX_OK)
    {
      return NGX_ERROR;
    }
  }

  ph = ngx_array_push(pa);
  if (ph == NULL) {
    return NGX_ERROR;
  }

  *ph = h;

#if (NGX_HTTP_CACHE)
  {
    u_char     *p, *last;
    ngx_int_t   n;

    if (u->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_CACHE_CONTROL) {
      return NGX_OK;
    }

    if (r->cache == NULL) {
      return NGX_OK;
    }

    if (r->cache->valid_sec != 0) {
      return NGX_OK;
    }

    p = h->value.data;
    last = p + h->value.len;

    if (ngx_strlcasestrn(p, last, (u_char *) "no-cache", 8 - 1) != NULL
        || ngx_strlcasestrn(p, last, (u_char *) "no-store", 8 - 1) != NULL
        || ngx_strlcasestrn(p, last, (u_char *) "private", 7 - 1) != NULL)
    {
      u->cacheable = 0;
      return NGX_OK;
    }

    p = ngx_strlcasestrn(p, last, (u_char *) "max-age=", 8 - 1);

    if (p == NULL) {
      return NGX_OK;
    }

    n = 0;

    for (p += 8; p < last; p++) {
      if (*p == ',' || *p == ';' || *p == ' ') {
        break;
      }

      if (*p >= '0' && *p <= '9') {
        n = n * 10 + *p - '0';
        continue;
      }

      u->cacheable = 0;
      return NGX_OK;
    }

    if (n == 0) {
      u->cacheable = 0;
      return NGX_OK;
    }

    r->cache->valid_sec = ngx_time() + n;
  }
#endif

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_expires(ngx_http_request_t *r, ngx_table_elt_t *h,
                                  ngx_uint_t offset)
{
  ngx_http_upstream_t  *u;

  u = r->upstream;
  u->headers_in.expires = h;

#if (NGX_HTTP_CACHE)
  {
    time_t  expires;

    if (u->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_EXPIRES) {
      return NGX_OK;
    }

    if (r->cache == NULL) {
      return NGX_OK;
    }

    if (r->cache->valid_sec != 0) {
      return NGX_OK;
    }

    expires = ngx_http_parse_time(h->value.data, h->value.len);

    if (expires == NGX_ERROR || expires < ngx_time()) {
      u->cacheable = 0;
      return NGX_OK;
    }

    r->cache->valid_sec = expires;
  }
#endif

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_accel_expires(ngx_http_request_t *r,
                                        ngx_table_elt_t *h, ngx_uint_t offset)
{
  ngx_http_upstream_t  *u;

  u = r->upstream;
  u->headers_in.x_accel_expires = h;

#if (NGX_HTTP_CACHE)
  {
    u_char     *p;
    size_t      len;
    ngx_int_t   n;

    if (u->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_XA_EXPIRES) {
      return NGX_OK;
    }

    if (r->cache == NULL) {
      return NGX_OK;
    }

    len = h->value.len;
    p = h->value.data;

    if (p[0] != '@') {
      n = ngx_atoi(p, len);

      switch (n) {
        case 0:
          u->cacheable = 0;
        case NGX_ERROR:
          return NGX_OK;

        default:
          r->cache->valid_sec = ngx_time() + n;
          return NGX_OK;
      }
    }

    p++;
    len--;

    n = ngx_atoi(p, len);

    if (n != NGX_ERROR) {
      r->cache->valid_sec = n;
    }
  }
#endif

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_limit_rate(ngx_http_request_t *r, ngx_table_elt_t *h,
                                     ngx_uint_t offset)
{
  ngx_int_t             n;
  ngx_http_upstream_t  *u;

  u = r->upstream;
  u->headers_in.x_accel_limit_rate = h;

  if (u->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_XA_LIMIT_RATE) {
    return NGX_OK;
  }

  n = ngx_atoi(h->value.data, h->value.len);

  if (n != NGX_ERROR) {
    r->limit_rate = (size_t) n;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_buffering(ngx_http_request_t *r, ngx_table_elt_t *h,
                                    ngx_uint_t offset)
{
  u_char                c0, c1, c2;
  ngx_http_upstream_t  *u;

  u = r->upstream;

  if (u->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_XA_BUFFERING) {
    return NGX_OK;
  }

  if (u->conf->change_buffering) {

    if (h->value.len == 2) {
      c0 = ngx_tolower(h->value.data[0]);
      c1 = ngx_tolower(h->value.data[1]);

      if (c0 == 'n' && c1 == 'o') {
        u->buffering = 0;
      }

    } else if (h->value.len == 3) {
      c0 = ngx_tolower(h->value.data[0]);
      c1 = ngx_tolower(h->value.data[1]);
      c2 = ngx_tolower(h->value.data[2]);

      if (c0 == 'y' && c1 == 'e' && c2 == 's') {
        u->buffering = 1;
      }
    }
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_charset(ngx_http_request_t *r, ngx_table_elt_t *h,
                                  ngx_uint_t offset)
{
  if (r->upstream->conf->ignore_headers & NGX_HTTP_UPSTREAM_IGN_XA_CHARSET) {
    return NGX_OK;
  }

  r->headers_out.override_charset = &h->value;

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_connection(ngx_http_request_t *r, ngx_table_elt_t *h,
                                     ngx_uint_t offset)
{
  r->upstream->headers_in.connection = h;

  if (ngx_strlcasestrn(h->value.data, h->value.data + h->value.len,
                       (u_char *) "close", 5 - 1)
      != NULL)
  {
    r->upstream->headers_in.connection_close = 1;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_process_transfer_encoding(ngx_http_request_t *r,
                                            ngx_table_elt_t *h, ngx_uint_t offset)
{
  r->upstream->headers_in.transfer_encoding = h;

  if (ngx_strlcasestrn(h->value.data, h->value.data + h->value.len,
                       (u_char *) "chunked", 7 - 1)
      != NULL)
  {
    r->upstream->headers_in.chunked = 1;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_copy_header_line(ngx_http_request_t *r, ngx_table_elt_t *h,
                                   ngx_uint_t offset)
{
  ngx_table_elt_t  *ho, **ph;

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;

  if (offset) {
    ph = (ngx_table_elt_t **) ((char *) &r->headers_out + offset);
    *ph = ho;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_copy_multi_header_lines(ngx_http_request_t *r,
                                          ngx_table_elt_t *h, ngx_uint_t offset)
{
  ngx_array_t      *pa;
  ngx_table_elt_t  *ho, **ph;

  pa = (ngx_array_t *) ((char *) &r->headers_out + offset);

  if (pa->elts == NULL) {
    if (ngx_array_init(pa, r->pool, 2, sizeof(ngx_table_elt_t *)) != NGX_OK)
    {
      return NGX_ERROR;
    }
  }

  ph = ngx_array_push(pa);
  if (ph == NULL) {
    return NGX_ERROR;
  }

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;
  *ph = ho;

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_copy_content_type(ngx_http_request_t *r, ngx_table_elt_t *h,
                                    ngx_uint_t offset)
{
  u_char  *p, *last;

  r->headers_out.content_type_len = h->value.len;
  r->headers_out.content_type = h->value;
  r->headers_out.content_type_lowcase = NULL;

  for (p = h->value.data; *p; p++) {

    if (*p != ';') {
      continue;
    }

    last = p;

    while (*++p == ' ') { /* void */ }

    if (*p == '\0') {
      return NGX_OK;
    }

    if (ngx_strncasecmp(p, (u_char *) "charset=", 8) != 0) {
      continue;
    }

    p += 8;

    r->headers_out.content_type_len = last - h->value.data;

    if (*p == '"') {
      p++;
    }

    last = h->value.data + h->value.len;

    if (*(last - 1) == '"') {
      last--;
    }

    r->headers_out.charset.len = last - p;
    r->headers_out.charset.data = p;

    return NGX_OK;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_copy_last_modified(ngx_http_request_t *r, ngx_table_elt_t *h,
                                     ngx_uint_t offset)
{
  ngx_table_elt_t  *ho;

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;

  r->headers_out.last_modified = ho;

#if (NGX_HTTP_CACHE)

  if (r->upstream->cacheable) {
    r->headers_out.last_modified_time = ngx_http_parse_time(h->value.data,
                                                            h->value.len);
  }

#endif

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_rewrite_location(ngx_http_request_t *r, ngx_table_elt_t *h,
                                   ngx_uint_t offset)
{
  ngx_int_t         rc;
  ngx_table_elt_t  *ho;

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;

  if (r->upstream->rewrite_redirect) {
    rc = r->upstream->rewrite_redirect(r, ho, 0);

    if (rc == NGX_DECLINED) {
      return NGX_OK;
    }

    if (rc == NGX_OK) {
      r->headers_out.location = ho;

      ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                     "rewritten location: \"%V\"", &ho->value);
    }

    return rc;
  }

  if (ho->value.data[0] != '/') {
    r->headers_out.location = ho;
  }

  /*
   * we do not set r->headers_out.location here to avoid the handling
   * the local redirects without a host name by ngx_http_header_filter()
   */

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_rewrite_refresh(ngx_http_request_t *r, ngx_table_elt_t *h,
                                  ngx_uint_t offset)
{
  u_char           *p;
  ngx_int_t         rc;
  ngx_table_elt_t  *ho;

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;

  if (r->upstream->rewrite_redirect) {

    p = ngx_strcasestrn(ho->value.data, "url=", 4 - 1);

    if (p) {
      rc = r->upstream->rewrite_redirect(r, ho, p + 4 - ho->value.data);

    } else {
      return NGX_OK;
    }

    if (rc == NGX_DECLINED) {
      return NGX_OK;
    }

    if (rc == NGX_OK) {
      r->headers_out.refresh = ho;

      ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                     "rewritten refresh: \"%V\"", &ho->value);
    }

    return rc;
  }

  r->headers_out.refresh = ho;

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_rewrite_set_cookie(ngx_http_request_t *r, ngx_table_elt_t *h,
                                     ngx_uint_t offset)
{
  ngx_table_elt_t  *ho;

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;

  if (r->upstream->rewrite_cookie) {
    return r->upstream->rewrite_cookie(r, ho);
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_copy_allow_ranges(ngx_http_request_t *r,
                                    ngx_table_elt_t *h, ngx_uint_t offset)
{
  ngx_table_elt_t  *ho;

#if (NGX_HTTP_CACHE)

  if (r->cached) {
    r->allow_ranges = 1;
    return NGX_OK;

  }

#endif

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;

  r->headers_out.accept_ranges = ho;

  return NGX_OK;
}


#if (NGX_HTTP_GZIP)

static ngx_int_t
ngx_http_upstream_copy_content_encoding(ngx_http_request_t *r,
                                        ngx_table_elt_t *h, ngx_uint_t offset)
{
  ngx_table_elt_t  *ho;

  ho = ngx_list_push(&r->headers_out.headers);
  if (ho == NULL) {
    return NGX_ERROR;
  }

  *ho = *h;

  r->headers_out.content_encoding = ho;

  return NGX_OK;
}

#endif


static ngx_int_t
ngx_http_upstream_add_variables(ngx_conf_t *cf)
{
  ngx_http_variable_t  *var, *v;

  for (v = ngx_http_upstream_vars; v->name.len; v++) {
    var = ngx_http_add_variable(cf, &v->name, v->flags);
    if (var == NULL) {
      return NGX_ERROR;
    }

    var->get_handler = v->get_handler;
    var->data = v->data;
  }

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_addr_variable(ngx_http_request_t *r,
                                ngx_http_variable_value_t *v, uintptr_t data)
{
  u_char                     *p;
  size_t                      len;
  ngx_uint_t                  i;
  ngx_http_upstream_state_t  *state;

  v->valid = 1;
  v->no_cacheable = 0;
  v->not_found = 0;

  if (r->upstream_states == NULL || r->upstream_states->nelts == 0) {
    v->not_found = 1;
    return NGX_OK;
  }

  len = 0;
  state = r->upstream_states->elts;

  for (i = 0; i < r->upstream_states->nelts; i++) {
    if (state[i].peer) {
      len += state[i].peer->len + 2;

    } else {
      len += 3;
    }
  }

  p = ngx_pnalloc(r->pool, len);
  if (p == NULL) {
    return NGX_ERROR;
  }

  v->data = p;

  i = 0;

  for ( ;; ) {
    if (state[i].peer) {
      p = ngx_cpymem(p, state[i].peer->data, state[i].peer->len);
    }

    if (++i == r->upstream_states->nelts) {
      break;
    }

    if (state[i].peer) {
      *p++ = ',';
      *p++ = ' ';

    } else {
      *p++ = ' ';
      *p++ = ':';
      *p++ = ' ';

      if (++i == r->upstream_states->nelts) {
        break;
      }

      continue;
    }
  }

  v->len = p - v->data;

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_status_variable(ngx_http_request_t *r,
                                  ngx_http_variable_value_t *v, uintptr_t data)
{
  u_char                     *p;
  size_t                      len;
  ngx_uint_t                  i;
  ngx_http_upstream_state_t  *state;

  v->valid = 1;
  v->no_cacheable = 0;
  v->not_found = 0;

  if (r->upstream_states == NULL || r->upstream_states->nelts == 0) {
    v->not_found = 1;
    return NGX_OK;
  }

  len = r->upstream_states->nelts * (3 + 2);

  p = ngx_pnalloc(r->pool, len);
  if (p == NULL) {
    return NGX_ERROR;
  }

  v->data = p;

  i = 0;
  state = r->upstream_states->elts;

  for ( ;; ) {
    if (state[i].status) {
      p = ngx_sprintf(p, "%ui", state[i].status);

    } else {
      *p++ = '-';
    }

    if (++i == r->upstream_states->nelts) {
      break;
    }

    if (state[i].peer) {
      *p++ = ',';
      *p++ = ' ';

    } else {
      *p++ = ' ';
      *p++ = ':';
      *p++ = ' ';

      if (++i == r->upstream_states->nelts) {
        break;
      }

      continue;
    }
  }

  v->len = p - v->data;

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_response_time_variable(ngx_http_request_t *r,
                                         ngx_http_variable_value_t *v, uintptr_t data)
{
  u_char                     *p;
  size_t                      len;
  ngx_uint_t                  i;
  ngx_msec_int_t              ms;
  ngx_http_upstream_state_t  *state;

  v->valid = 1;
  v->no_cacheable = 0;
  v->not_found = 0;

  if (r->upstream_states == NULL || r->upstream_states->nelts == 0) {
    v->not_found = 1;
    return NGX_OK;
  }

  len = r->upstream_states->nelts * (NGX_TIME_T_LEN + 4 + 2);

  p = ngx_pnalloc(r->pool, len);
  if (p == NULL) {
    return NGX_ERROR;
  }

  v->data = p;

  i = 0;
  state = r->upstream_states->elts;

  for ( ;; ) {
    if (state[i].status) {
      ms = (ngx_msec_int_t)
          (state[i].response_sec * 1000 + state[i].response_msec);
      ms = ngx_max(ms, 0);
      p = ngx_sprintf(p, "%d.%03d", ms / 1000, ms % 1000);

    } else {
      *p++ = '-';
    }

    if (++i == r->upstream_states->nelts) {
      break;
    }

    if (state[i].peer) {
      *p++ = ',';
      *p++ = ' ';

    } else {
      *p++ = ' ';
      *p++ = ':';
      *p++ = ' ';

      if (++i == r->upstream_states->nelts) {
        break;
      }

      continue;
    }
  }

  v->len = p - v->data;

  return NGX_OK;
}


static ngx_int_t
ngx_http_upstream_response_length_variable(ngx_http_request_t *r,
                                           ngx_http_variable_value_t *v, uintptr_t data)
{
  u_char                     *p;
  size_t                      len;
  ngx_uint_t                  i;
  ngx_http_upstream_state_t  *state;

  v->valid = 1;
  v->no_cacheable = 0;
  v->not_found = 0;

  if (r->upstream_states == NULL || r->upstream_states->nelts == 0) {
    v->not_found = 1;
    return NGX_OK;
  }

  len = r->upstream_states->nelts * (NGX_OFF_T_LEN + 2);

  p = ngx_pnalloc(r->pool, len);
  if (p == NULL) {
    return NGX_ERROR;
  }

  v->data = p;

  i = 0;
  state = r->upstream_states->elts;

  for ( ;; ) {
    p = ngx_sprintf(p, "%O", state[i].response_length);

    if (++i == r->upstream_states->nelts) {
      break;
    }

    if (state[i].peer) {
      *p++ = ',';
      *p++ = ' ';

    } else {
      *p++ = ' ';
      *p++ = ':';
      *p++ = ' ';

      if (++i == r->upstream_states->nelts) {
        break;
      }

      continue;
    }
  }

  v->len = p - v->data;

  return NGX_OK;
}


ngx_int_t
ngx_http_upstream_header_variable(ngx_http_request_t *r,
                                  ngx_http_variable_value_t *v, uintptr_t data)
{
  if (r->upstream == NULL) {
    v->not_found = 1;
    return NGX_OK;
  }

  return ngx_http_variable_unknown_header(v, (ngx_str_t *) data,
                                          &r->upstream->headers_in.headers.part,
                                          sizeof("upstream_http_") - 1);
}


#if (NGX_HTTP_CACHE)

ngx_int_t
ngx_http_upstream_cache_status(ngx_http_request_t *r,
                               ngx_http_variable_value_t *v, uintptr_t data)
{
  ngx_uint_t  n;

  if (r->upstream == NULL || r->upstream->cache_status == 0) {
    v->not_found = 1;
    return NGX_OK;
  }

  n = r->upstream->cache_status - 1;

  v->valid = 1;
  v->no_cacheable = 0;
  v->not_found = 0;
  v->len = ngx_http_cache_status[n].len;
  v->data = ngx_http_cache_status[n].data;

  return NGX_OK;
}

#endif


static char *
ngx_http_upstream(ngx_conf_t *cf, ngx_command_t *cmd, void *dummy)
{
  char                          *rv;
  void                          *mconf;
  ngx_str_t                     *value;
  ngx_url_t                      u;
  ngx_uint_t                     m;
  ngx_conf_t                     pcf;
  ngx_http_module_t             *module;
  ngx_http_conf_ctx_t           *ctx, *http_ctx;
  ngx_http_upstream_srv_conf_t  *uscf;

  ngx_memzero(&u, sizeof(ngx_url_t));

  value = cf->args->elts;
  u.host = value[1];
  u.no_resolve = 1;

  uscf = ngx_http_upstream_add(cf, &u, NGX_HTTP_UPSTREAM_CREATE
                               |NGX_HTTP_UPSTREAM_WEIGHT
                               |NGX_HTTP_UPSTREAM_MAX_FAILS
                               |NGX_HTTP_UPSTREAM_FAIL_TIMEOUT
                               |NGX_HTTP_UPSTREAM_DOWN
                               |NGX_HTTP_UPSTREAM_BACKUP);
  if (uscf == NULL) {
    return NGX_CONF_ERROR;
  }


  ctx = ngx_pcalloc(cf->pool, sizeof(ngx_http_conf_ctx_t));
  if (ctx == NULL) {
    return NGX_CONF_ERROR;
  }

  http_ctx = cf->ctx;
  ctx->main_conf = http_ctx->main_conf;

  /* the upstream{}'s srv_conf */

  ctx->srv_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
  if (ctx->srv_conf == NULL) {
    return NGX_CONF_ERROR;
  }

  ctx->srv_conf[ngx_http_upstream_module.ctx_index] = uscf;

  uscf->srv_conf = ctx->srv_conf;


  /* the upstream{}'s loc_conf */

  ctx->loc_conf = ngx_pcalloc(cf->pool, sizeof(void *) * ngx_http_max_module);
  if (ctx->loc_conf == NULL) {
    return NGX_CONF_ERROR;
  }

  for (m = 0; ngx_modules[m]; m++) {
    if (ngx_modules[m]->type != NGX_HTTP_MODULE) {
      continue;
    }

    module = ngx_modules[m]->ctx;

    if (module->create_srv_conf) {
      mconf = module->create_srv_conf(cf);
      if (mconf == NULL) {
        return NGX_CONF_ERROR;
      }

      ctx->srv_conf[ngx_modules[m]->ctx_index] = mconf;
    }

    if (module->create_loc_conf) {
      mconf = module->create_loc_conf(cf);
      if (mconf == NULL) {
        return NGX_CONF_ERROR;
      }

      ctx->loc_conf[ngx_modules[m]->ctx_index] = mconf;
    }
  }


  /* parse inside upstream{} */

  pcf = *cf;
  cf->ctx = ctx;
  cf->cmd_type = NGX_HTTP_UPS_CONF;

  rv = ngx_conf_parse(cf, NULL);

  *cf = pcf;

  if (rv != NGX_CONF_OK) {
    return rv;
  }

  if (uscf->servers == NULL) {
    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                       "no servers are inside upstream");
    return NGX_CONF_ERROR;
  }

  return rv;
}


static char *
ngx_http_upstream_server(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
  ngx_http_upstream_srv_conf_t  *uscf = conf;

  time_t                       fail_timeout;
  ngx_str_t                   *value, s;
  ngx_url_t                    u;
  ngx_int_t                    weight, max_fails;
  ngx_uint_t                   i;
  ngx_http_upstream_server_t  *us;

  if (uscf->servers == NULL) {
    uscf->servers = ngx_array_create(cf->pool, 4,
                                     sizeof(ngx_http_upstream_server_t));
    if (uscf->servers == NULL) {
      return NGX_CONF_ERROR;
    }
  }

  us = ngx_array_push(uscf->servers);
  if (us == NULL) {
    return NGX_CONF_ERROR;
  }

  ngx_memzero(us, sizeof(ngx_http_upstream_server_t));

  value = cf->args->elts;

  ngx_memzero(&u, sizeof(ngx_url_t));

  u.url = value[1];
  u.default_port = 80;

  if (ngx_parse_url(cf->pool, &u) != NGX_OK) {
    if (u.err) {
      ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                         "%s in upstream \"%V\"", u.err, &u.url);
    }

    return NGX_CONF_ERROR;
  }

  weight = 1;
  max_fails = 1;
  fail_timeout = 10;

  for (i = 2; i < cf->args->nelts; i++) {

    if (ngx_strncmp(value[i].data, "weight=", 7) == 0) {

      if (!(uscf->flags & NGX_HTTP_UPSTREAM_WEIGHT)) {
        goto invalid;
      }

      weight = ngx_atoi(&value[i].data[7], value[i].len - 7);

      if (weight == NGX_ERROR || weight == 0) {
        goto invalid;
      }

      continue;
    }

    if (ngx_strncmp(value[i].data, "max_fails=", 10) == 0) {

      if (!(uscf->flags & NGX_HTTP_UPSTREAM_MAX_FAILS)) {
        goto invalid;
      }

      max_fails = ngx_atoi(&value[i].data[10], value[i].len - 10);

      if (max_fails == NGX_ERROR) {
        goto invalid;
      }

      continue;
    }

    if (ngx_strncmp(value[i].data, "fail_timeout=", 13) == 0) {

      if (!(uscf->flags & NGX_HTTP_UPSTREAM_FAIL_TIMEOUT)) {
        goto invalid;
      }

      s.len = value[i].len - 13;
      s.data = &value[i].data[13];

      fail_timeout = ngx_parse_time(&s, 1);

      if (fail_timeout == (time_t) NGX_ERROR) {
        goto invalid;
      }

      continue;
    }

    if (ngx_strncmp(value[i].data, "backup", 6) == 0) {

      if (!(uscf->flags & NGX_HTTP_UPSTREAM_BACKUP)) {
        goto invalid;
      }

      us->backup = 1;

      continue;
    }

    if (ngx_strncmp(value[i].data, "down", 4) == 0) {

      if (!(uscf->flags & NGX_HTTP_UPSTREAM_DOWN)) {
        goto invalid;
      }

      us->down = 1;

      continue;
    }

    goto invalid;
  }

  us->addrs = u.addrs;
  us->naddrs = u.naddrs;
  us->weight = weight;
  us->max_fails = max_fails;
  us->fail_timeout = fail_timeout;

  return NGX_CONF_OK;

invalid:

  ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                     "invalid parameter \"%V\"", &value[i]);

  return NGX_CONF_ERROR;
}


ngx_http_upstream_srv_conf_t *
ngx_http_upstream_add(ngx_conf_t *cf, ngx_url_t *u, ngx_uint_t flags)
{
  ngx_uint_t                      i;
  ngx_http_upstream_server_t     *us;
  ngx_http_upstream_srv_conf_t   *uscf, **uscfp;
  ngx_http_upstream_main_conf_t  *umcf;

  if (!(flags & NGX_HTTP_UPSTREAM_CREATE)) {

    if (ngx_parse_url(cf->pool, u) != NGX_OK) {
      if (u->err) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "%s in upstream \"%V\"", u->err, &u->url);
      }

      return NULL;
    }
  }

  umcf = ngx_http_conf_get_module_main_conf(cf, ngx_http_upstream_module);

  uscfp = umcf->upstreams.elts;

  for (i = 0; i < umcf->upstreams.nelts; i++) {

    if (uscfp[i]->host.len != u->host.len
        || ngx_strncasecmp(uscfp[i]->host.data, u->host.data, u->host.len)
        != 0)
    {
      continue;
    }

    if ((flags & NGX_HTTP_UPSTREAM_CREATE)
        && (uscfp[i]->flags & NGX_HTTP_UPSTREAM_CREATE))
    {
      ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                         "duplicate upstream \"%V\"", &u->host);
      return NULL;
    }

    if ((uscfp[i]->flags & NGX_HTTP_UPSTREAM_CREATE) && u->port) {
      ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                         "upstream \"%V\" may not have port %d",
                         &u->host, u->port);
      return NULL;
    }

    if ((flags & NGX_HTTP_UPSTREAM_CREATE) && uscfp[i]->port) {
      ngx_log_error(NGX_LOG_WARN, cf->log, 0,
                    "upstream \"%V\" may not have port %d in %s:%ui",
                    &u->host, uscfp[i]->port,
                    uscfp[i]->file_name, uscfp[i]->line);
      return NULL;
    }

    if (uscfp[i]->port != u->port) {
      continue;
    }

    if (uscfp[i]->default_port && u->default_port
        && uscfp[i]->default_port != u->default_port)
    {
      continue;
    }

    if (flags & NGX_HTTP_UPSTREAM_CREATE) {
      uscfp[i]->flags = flags;
    }

    return uscfp[i];
  }

  uscf = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_srv_conf_t));
  if (uscf == NULL) {
    return NULL;
  }

  uscf->flags = flags;
  uscf->host = u->host;
  uscf->file_name = cf->conf_file->file.name.data;
  uscf->line = cf->conf_file->line;
  uscf->port = u->port;
  uscf->default_port = u->default_port;

  if (u->naddrs == 1) {
    uscf->servers = ngx_array_create(cf->pool, 1,
                                     sizeof(ngx_http_upstream_server_t));
    if (uscf->servers == NULL) {
      return NGX_CONF_ERROR;
    }

    us = ngx_array_push(uscf->servers);
    if (us == NULL) {
      return NGX_CONF_ERROR;
    }

    ngx_memzero(us, sizeof(ngx_http_upstream_server_t));

    us->addrs = u->addrs;
    us->naddrs = u->naddrs;
  }

  uscfp = ngx_array_push(&umcf->upstreams);
  if (uscfp == NULL) {
    return NULL;
  }

  *uscfp = uscf;

  return uscf;
}


char *
ngx_http_upstream_bind_set_slot(ngx_conf_t *cf, ngx_command_t *cmd,
                                void *conf)
{
  char  *p = conf;

  ngx_int_t     rc;
  ngx_str_t    *value;
  ngx_addr_t  **paddr;

  paddr = (ngx_addr_t **) (p + cmd->offset);

  *paddr = ngx_palloc(cf->pool, sizeof(ngx_addr_t));
  if (*paddr == NULL) {
    return NGX_CONF_ERROR;
  }

  value = cf->args->elts;

  rc = ngx_parse_addr(cf->pool, *paddr, value[1].data, value[1].len);

  switch (rc) {
    case NGX_OK:
      (*paddr)->name = value[1];
      return NGX_CONF_OK;

    case NGX_DECLINED:
      ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                         "invalid address \"%V\"", &value[1]);
    default:
      return NGX_CONF_ERROR;
  }
}


char *
ngx_http_upstream_param_set_slot(ngx_conf_t *cf, ngx_command_t *cmd,
                                 void *conf)
{
  char  *p = conf;

  ngx_str_t                   *value;
  ngx_array_t                **a;
  ngx_http_upstream_param_t   *param;

  a = (ngx_array_t **) (p + cmd->offset);

  if (*a == NULL) {
    *a = ngx_array_create(cf->pool, 4, sizeof(ngx_http_upstream_param_t));
    if (*a == NULL) {
      return NGX_CONF_ERROR;
    }
  }

  param = ngx_array_push(*a);
  if (param == NULL) {
    return NGX_CONF_ERROR;
  }

  value = cf->args->elts;

  param->key = value[1];
  param->value = value[2];
  param->skip_empty = 0;

  if (cf->args->nelts == 4) {
    if (ngx_strcmp(value[3].data, "if_not_empty") != 0) {
      ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                         "invalid parameter \"%V\"", &value[3]);
      return NGX_CONF_ERROR;
    }

    param->skip_empty = 1;
  }

  return NGX_CONF_OK;
}


ngx_int_t
ngx_http_upstream_hide_headers_hash(ngx_conf_t *cf,
                                    ngx_http_upstream_conf_t *conf, ngx_http_upstream_conf_t *prev,
                                    ngx_str_t *default_hide_headers, ngx_hash_init_t *hash)
{
  ngx_str_t       *h;
  ngx_uint_t       i, j;
  ngx_array_t      hide_headers;
  ngx_hash_key_t  *hk;

  if (conf->hide_headers == NGX_CONF_UNSET_PTR
      && conf->pass_headers == NGX_CONF_UNSET_PTR)
  {
    conf->hide_headers_hash = prev->hide_headers_hash;

    if (conf->hide_headers_hash.buckets
#if (NGX_HTTP_CACHE)
        && ((conf->cache == NULL) == (prev->cache == NULL))
#endif
        )
    {
      return NGX_OK;
    }

    conf->hide_headers = prev->hide_headers;
    conf->pass_headers = prev->pass_headers;

  } else {
    if (conf->hide_headers == NGX_CONF_UNSET_PTR) {
      conf->hide_headers = prev->hide_headers;
    }

    if (conf->pass_headers == NGX_CONF_UNSET_PTR) {
      conf->pass_headers = prev->pass_headers;
    }
  }

  if (ngx_array_init(&hide_headers, cf->temp_pool, 4, sizeof(ngx_hash_key_t))
      != NGX_OK)
  {
    return NGX_ERROR;
  }

  for (h = default_hide_headers; h->len; h++) {
    hk = ngx_array_push(&hide_headers);
    if (hk == NULL) {
      return NGX_ERROR;
    }

    hk->key = *h;
    hk->key_hash = ngx_hash_key_lc(h->data, h->len);
    hk->value = (void *) 1;
  }

  if (conf->hide_headers != NGX_CONF_UNSET_PTR) {

    h = conf->hide_headers->elts;

    for (i = 0; i < conf->hide_headers->nelts; i++) {

      hk = hide_headers.elts;

      for (j = 0; j < hide_headers.nelts; j++) {
        if (ngx_strcasecmp(h[i].data, hk[j].key.data) == 0) {
          goto exist;
        }
      }

      hk = ngx_array_push(&hide_headers);
      if (hk == NULL) {
        return NGX_ERROR;
      }

      hk->key = h[i];
      hk->key_hash = ngx_hash_key_lc(h[i].data, h[i].len);
      hk->value = (void *) 1;

   exist:

      continue;
    }
  }

  if (conf->pass_headers != NGX_CONF_UNSET_PTR) {

    h = conf->pass_headers->elts;
    hk = hide_headers.elts;

    for (i = 0; i < conf->pass_headers->nelts; i++) {
      for (j = 0; j < hide_headers.nelts; j++) {

        if (hk[j].key.data == NULL) {
          continue;
        }

        if (ngx_strcasecmp(h[i].data, hk[j].key.data) == 0) {
          hk[j].key.data = NULL;
          break;
        }
      }
    }
  }

  hash->hash = &conf->hide_headers_hash;
  hash->key = ngx_hash_key_lc;
  hash->pool = cf->pool;
  hash->temp_pool = NULL;

  return ngx_hash_init(hash, hide_headers.elts, hide_headers.nelts);
}


static void *
ngx_http_upstream_create_main_conf(ngx_conf_t *cf)
{
  ngx_http_upstream_main_conf_t  *umcf;

  umcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_upstream_main_conf_t));
  if (umcf == NULL) {
    return NULL;
  }

  if (ngx_array_init(&umcf->upstreams, cf->pool, 4,
                     sizeof(ngx_http_upstream_srv_conf_t *))
      != NGX_OK)
  {
    return NULL;
  }

  return umcf;
}


static char *
ngx_http_upstream_init_main_conf(ngx_conf_t *cf, void *conf)
{
  ngx_http_upstream_main_conf_t  *umcf = conf;

  ngx_uint_t                      i;
  ngx_array_t                     headers_in;
  ngx_hash_key_t                 *hk;
  ngx_hash_init_t                 hash;
  ngx_http_upstream_init_pt       init;
  ngx_http_upstream_header_t     *header;
  ngx_http_upstream_srv_conf_t  **uscfp;

  uscfp = umcf->upstreams.elts;

  for (i = 0; i < umcf->upstreams.nelts; i++) {

    init = uscfp[i]->peer.init_upstream ? uscfp[i]->peer.init_upstream:
        ngx_http_upstream_init_round_robin;

    if (init(cf, uscfp[i]) != NGX_OK) {
      return NGX_CONF_ERROR;
    }
  }


  /* upstream_headers_in_hash */

  if (ngx_array_init(&headers_in, cf->temp_pool, 32, sizeof(ngx_hash_key_t))
      != NGX_OK)
  {
    return NGX_CONF_ERROR;
  }

  for (header = ngx_http_upstream_headers_in; header->name.len; header++) {
    hk = ngx_array_push(&headers_in);
    if (hk == NULL) {
      return NGX_CONF_ERROR;
    }

    hk->key = header->name;
    hk->key_hash = ngx_hash_key_lc(header->name.data, header->name.len);
    hk->value = header;
  }

  hash.hash = &umcf->headers_in_hash;
  hash.key = ngx_hash_key_lc;
  hash.max_size = 512;
  hash.bucket_size = ngx_align(64, ngx_cacheline_size);
  hash.name = "upstream_headers_in_hash";
  hash.pool = cf->pool;
  hash.temp_pool = NULL;

  if (ngx_hash_init(&hash, headers_in.elts, headers_in.nelts) != NGX_OK) {
    return NGX_CONF_ERROR;
  }

  return NGX_CONF_OK;
}
